diff --git a/examples/ex_4.c b/examples/ex_4.c
index 3e2ca86..bafadda 100644
--- a/examples/ex_4.c
+++ b/examples/ex_4.c
@@ -86,9 +86,37 @@ print_array(int *array, size_t l)
 }
 
 bool
-has_span(int *array, size_t n, int x, int l)
+has_span(int *array, size_t l, size_t n)
 {
-  if (n == 0 || l <= 0) {
+  if (n == 0 || l == 0 || n > l) {
+    return false;
+  }
+
+  int sorted[l];
+  memcpy(sorted, array, sizeof(int) * l);
+  qsort(sorted, l, sizeof(int), compare_ints);
+
+  for (size_t i = 0; i <= l - n; i++) {
+    if (sorted[i] + n - 1 == sorted[i + n - 1]) {
+#if 0
+      fprintf(stderr, "Found span: ");
+      for (size_t j = i; j < i + n; j++) {
+        fprintf(stderr, "%d ", sorted[j]);
+      }
+       fprintf(stderr, "\n");
+#endif
+      __diag("Found span: [%d, %d], length: %zu\n", sorted[i], sorted[i + n - 1], n);
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+is_span(int *array, size_t n, int x, int l)
+{
+  if (n == 0 || l < 0) {
     return false;
   }
 
@@ -105,7 +133,6 @@ has_span(int *array, size_t n, int x, int l)
       }
     }
   }
-
   return false; // Span not found
 }
 
@@ -113,11 +140,10 @@ void
 print_spans(int *array, size_t n)
 {
   int a[n];
-  size_t start = 0;
-  size_t end = 0;
+  size_t start = 0, end = 0;
 
   if (n == 0) {
-    printf("Array is empty\n");
+    fprintf(stderr, "Array is empty\n");
     return;
   }
 
@@ -130,9 +156,9 @@ print_spans(int *array, size_t n)
     } else {
       // Print the current span
       if (start == end) {
-        printf("[%d] ", a[start]);
+        fprintf(stderr, "[%d] ", a[start]);
       } else {
-        printf("[%d, %d] ", a[start], a[end]);
+        fprintf(stderr, "[%d, %d] ", a[start], a[end]);
       }
       // Move to the next span
       start = i;
@@ -142,9 +168,9 @@ print_spans(int *array, size_t n)
 
   // Print the last span if needed
   if (start == end) {
-    printf("[%d]\n", a[start]);
+    fprintf(stderr, "[%d]\n", a[start]);
   } else {
-    printf("[%d, %d]\n", a[start], a[end]);
+    fprintf(stderr, "[%d, %d]\n", a[start], a[end]);
   }
 }
 
@@ -173,15 +199,68 @@ main(void)
   setbuf(stdout, 0);
   setbuf(stderr, 0);
 
-  // int foo[] = {1, 2, 3, 5, 7, 8 ,9, 10, 21};
-  // print_spans(foo, sizeof(foo) / sizeof(foo[0]));
-  // exit(0);
-
-  // start with a 1KiB buffer, TEST_ARRAY_SIZE bits
-  uint8_t *buf = calloc(TEST_ARRAY_SIZE * 3, sizeof(uint8_t));
+  // start with a 3KiB buffer, TEST_ARRAY_SIZE bits
+  uint8_t *buf = calloc(3 * 1024, sizeof(uint8_t));
 
   // create the sparse bitmap
-  sparsemap_t *map = sparsemap(buf, sizeof(uint8_t) * 1024 * 3, 0);
+  sparsemap_t *map = sparsemap(buf, sizeof(uint8_t) * 3 * 1024, 0);
+
+  // seed the PRNG
+#ifdef SEED
+  __random_seed(&prng, 8675309);
+#else
+  __random_seed(&prng, (unsigned int)time(NULL) ^ getpid());
+#endif
+
+  for (i = 0; i < TEST_ARRAY_SIZE; i++) {
+    uint32_t r = __random(&prng);
+    array[i] = (int)r % (4 * TEST_ARRAY_SIZE);
+    if (array[i] < 0) {
+      i--;
+    }
+    for (int j = 0; j < i; j++) {
+      if (array[j] == array[i]) {
+        i--;
+      }
+    }
+  }
+  // create a span of at least 8 for testing between 141 and 153
+  int j = 143;
+  for (i = 0; i < 8; i++) {
+    uint32_t r = __random(&prng) % TEST_ARRAY_SIZE;
+    array[r] = j++;
+  }
+  // randomize setting the bits on
+  shuffle(&prng, array, TEST_ARRAY_SIZE);
+  print_spans(array, TEST_ARRAY_SIZE);
+
+  // set all the bits on in a random order
+  for (i = 0; i < TEST_ARRAY_SIZE; i++) {
+    //__diag("set %d\n", array[i]);
+    sparsemap_set(map, array[i], true);
+    assert(sparsemap_is_set(map, array[i]) == true);
+  }
+
+  for (size_t len = 1; len < TEST_ARRAY_SIZE; len++) {
+    // for (size_t len = 1; len <= 1; len++) {
+    // for (size_t len = 2; len <= 2; len++) {
+    // for (size_t len = 3; len <= 3; len++) {
+    // for (size_t len = 8; len <= 8; len++) {
+    __diag("================> %lu\n", len);
+    has_span(array, TEST_ARRAY_SIZE, len);
+    size_t l = sparsemap_span(map, 0, len);
+    __diag("Found span in map starting at %lu of length %lu\n", l, len);
+    __diag("is_span(%lu, %lu) == %s\n", l, len, is_span(array, TEST_ARRAY_SIZE, l, len) ? "yes" : "no");
+    i = (int)l;
+    do {
+      bool set = sparsemap_is_set(map, i);
+      if (set) {
+        __diag("verified %d was set\n", i);
+      } else {
+        __diag("darn, %d was not really set, %s\n", i, was_set(i, array) ? "but we thought it was" : "because it wasn't");
+      }
+    } while (++i < l + len);
+  }
 
 #if 0
   for (i = 0; i < 8; i++) sparsemap_set(map, i, true);
@@ -230,60 +309,5 @@ main(void)
   sparsemap_clear(map);
 #endif
 
-  // seed the PRNG
-#ifdef SEED
-  __random_seed(&prng, 8675309);
-#else
-  __random_seed(&prng, (unsigned int)time(NULL) ^ getpid());
-#endif
-
-  for (i = 0; i < TEST_ARRAY_SIZE; i++) {
-    uint32_t r = __random(&prng);
-    array[i] = (int)r % (4 * TEST_ARRAY_SIZE);
-    if (array[i] < 0) {
-      i--;
-    }
-    for (int j = 0; j < i; j++) {
-      if (array[j] == array[i]) {
-        i--;
-      }
-    }
-  }
-  // create a span of at least 8 for testing between 141 and 153
-  int j = 143;
-  for (i = 0; i < 8; i++) {
-    uint32_t r = __random(&prng) % TEST_ARRAY_SIZE;
-    array[r] = j++;
-  }
-  // randomize setting the bits on
-  shuffle(&prng, array, TEST_ARRAY_SIZE);
-  print_spans(array, TEST_ARRAY_SIZE);
-
-  // set all the bits on in a random order
-  for (i = 0; i < TEST_ARRAY_SIZE; i++) {
-    //__diag("set %d\n", array[i]);
-    sparsemap_set(map, array[i], true);
-    assert(sparsemap_is_set(map, array[i]) == true);
-  }
-
-  for (size_t len = 0; len < TEST_ARRAY_SIZE; len++) {
-  //for (size_t len = 1; len <= 1; len++) {
-  //for (size_t len = 2; len <= 2; len++) {
-  //for (size_t len = 3; len <= 3; len++) {
-  //for (size_t len = 8; len <= 8; len++) {
-    __diag("================> %lu\n", len);
-    size_t l = sparsemap_span(map, 0, len);
-    __diag("found span of %lu at %lu\n", len, l);
-    __diag("is_span(%lu, %lu) == %s\n", l, len, has_span(array, TEST_ARRAY_SIZE, l, len) ? "yes" : "no");
-    for (i = (int)l; i < l + len; i++) {
-      bool set = sparsemap_is_set(map, i);
-      if (set) {
-        __diag("verified %d was set\n", i);
-      } else {
-        __diag("darn, %d was not really set, %s\n", i, was_set(i, array) ? "but we thought it was" : "because it wasn't");
-      }
-    }
-  }
-
   return 0;
 }