Minor corrections

C/p041.c

@@ -49,6 +49,11 @@ int main(int argc, char **argv)
 int count_digits(int n)
 {
    int i = 0;
+   
+   if(n == 0)
+   {
+      return 1;
+   }
 
    while(n > 0)
    {

C/p057.c

@@ -67,6 +67,11 @@ int count_digits(mpz_t n)
    int count = 0;
    mpz_t value;
 
+   if(mpz_cmp_ui(n, 0) == 0)
+   {
+      return 1;
+   }
+
    mpz_init_set(value, n);
 
    while(mpz_cmp_ui(value, 0))