C语言使用递归法计算n的阶乘

#include <stdio.h>
long Fact(int n);
int main(){
    int n;
    long ret;
    printf("Input n:");
    scanf("%d",&n);
    ret =Fact(n);
    if(ret==-1)
        printf("n<0, data error!\n");
    else
        printf("%d! = %ld\n",n,ret);
    return 0;
}

long Fact(int n){
    if(n<0)
        return -1;
    else if (n==0||n==1)
        return 1;
    else
        return (n*Fact(n-1));

}