diff --git a/41 b/41
new file mode 100755
index 0000000..9f45963
Binary files /dev/null and b/41 differ
diff --git a/41.c b/41.c
new file mode 100644
index 0000000..6e20bb1
--- /dev/null
+++ b/41.c
@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <stdbool.h>
+#include "primes.h"
+
+bool isPandigital (int n) {
+    if (n < 1 || n > 987654321)
+        return false;
+    
+    int digits = floor (log10 (n)) + 1;
+    bool* seen = calloc (digits, sizeof (bool));
+    while (n > 0) {
+        int digit = n % 10;
+        if (digit == 0 || seen[digit - 1])
+            return false;
+        seen[digit - 1] = true;
+        n /= 10;
+    }
+    for (int d = 0; d < digits; d++) {
+        if (!seen[d])
+            return false;
+    }
+    return true;
+}
+
+int main () {
+    long* primes;
+    bool* primesTable;
+    long numPrimes = listOfPrimes (7654321, &primes, &primesTable);
+    for (long i = numPrimes; i > 0; i--) {
+        if (isPandigital (primes[i])) {
+            printf ("%d\n", primes[i]);
+            break;
+        }
+    }
+}
diff --git a/primes.c b/primes.c
index b6e517a..7ee57b0 100644
--- a/primes.c
+++ b/primes.c
@@ -8,12 +8,12 @@
  *  runs in O(sqrt(n))
  *
  */
-bool isPrime (int n) {
+bool isPrime (long n) {
     if (n == 0 || n == 1)
         return false;
 
-    int sqrtn = (int) sqrt (n);
-    for (int i = 2; i <= sqrtn; i++) {
+    long sqrtn = (long) sqrt (n);
+    for (long i = 2; i <= sqrtn; i++) {
         if (n % i == 0)
             return false;
     }
@@ -26,14 +26,14 @@ bool isPrime (int n) {
  *  runs in O(sqrt(n)/ln(n))
  *
  */
-bool isPrimeMem (int n, int* primes) {
+bool isPrimeMem (long n, long* primes) {
     if (n == 0 || n == 1)
         return false;
     if (n == 2 || n == 3)
         return true;
 
-    int sqrtn = (int) sqrt (n);
-    int i = 0;
+    long sqrtn = (long) sqrt (n);
+    long i = 0;
     while (primes[i] <= sqrtn) {
         if (n % primes[i++] == 0)
             return false;
@@ -58,7 +58,7 @@ bool isPrimeMem (int n, int* primes) {
  *
  */
 
-int listOfPrimes (int n, int** primes_ptr, bool** primesTable_ptr) {
+long listOfPrimes (long n, long** primes_ptr, bool** primesTable_ptr) {
     *primesTable_ptr = calloc (n + 1, sizeof (bool));
 
     if (n == 0 || n == 1) {
@@ -66,10 +66,10 @@ int listOfPrimes (int n, int** primes_ptr, bool** primesTable_ptr) {
         return 0;
     }
 
-    int numOfPrimesUpper = (int) (n/log(n) * 1.25506); 
-    *primes_ptr = malloc (sizeof (int) * numOfPrimesUpper);
-    int numOfPrimes = 0;
-    for (int i = 0; i <= n; i++) {
+    long numOfPrimesUpper = (long) (n/log(n) * 1.25506); 
+    *primes_ptr = malloc (sizeof (long) * numOfPrimesUpper);
+    long numOfPrimes = 0;
+    for (long i = 0; i <= n; i++) {
         if (isPrimeMem (i, *primes_ptr)) {
             (*primes_ptr)[numOfPrimes] = i;
             (*primesTable_ptr)[i] = true;
@@ -77,8 +77,8 @@ int listOfPrimes (int n, int** primes_ptr, bool** primesTable_ptr) {
         }
     }
     if (numOfPrimes < numOfPrimesUpper) {
-        int* tmp = realloc (*primes_ptr, 
-                            sizeof (int) * numOfPrimes);
+        long* tmp = realloc (*primes_ptr, 
+                             sizeof (long) * numOfPrimes);
         if (tmp != NULL)
             *primes_ptr = tmp;
     }
diff --git a/primes.h b/primes.h
index 40b3aee..dc4695b 100644
--- a/primes.h
+++ b/primes.h
@@ -1,4 +1,4 @@
-bool isPrime (int n);
-bool isPrimeMem (int n, int* primes);
-int listOfPrimes (int n, int** primes_ptr, bool** primesTable_ptr);
+bool isPrime (long n);
+bool isPrimeMem (long n, long* primes);
+long listOfPrimes (long n, long** primes_ptr, bool** primesTable_ptr);
 void sieveOfEratosthenes (int n, bool** primesTable_ptr);