#include <stdio.h>
#include <stdlib.h>

int fatorial(int n)
{
        if (n!=1)
                return(n * fatorial(n-1));
        else
                return 1;
}


int main(int argc, char *argv[])
{
        if(argc < 2)
        {
                printf("Usage: %s number\n", argv[0]);
                return(0);
        }

        fprintf(stderr, "fatorial de %s, é: %d", argv[1], fatorial(atoi(argv[1])));
        return 0;
}