废物是我

#include<stdio.h>//c语言菜鸟，可能是递归？
int jia(long int n)
{
    long sum=0;
    while(n)
    {
        sum+=n%10;
        n/=10;
    }
    return sum;
}
void shuhe(long int n)
{
    if(n<=9) printf("%ld",n);
    else
     {
        shuhe(jia(n));
     }
}
int main()
{
    long  int n;
    scanf("%ld",&n);
    shuhe(n);
}