#include <assert.h>
int factorial(int n) {
assert(n >= 0);
if(n == 0) return 1;
return n*factorial(n-1);
}
int main() {
printf("Factorial of %d is %d\n", 10, factorial(10));
printf("Factorial of %d is %d\n", -1, factorial(-1));
return 0;