UVA_11332_Summing_Digits

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

long suma_dig(int n){
    long suma,rest;
    suma=0;
    while(10<=n){
        rest=n%10;
        n=n/10;

        if(n<10) {
            suma=suma+n;
        }
        suma=suma+rest;
    }
    return suma;
}

long f(int n){
    int suma;
    if(n<10) return n;
    suma=suma_dig(n);
    n=suma;
    f(n);
}
int main(int argc, char** argv) {
    long n,rpta;
    while (scanf("%lu",&n)){
        if(n==0)break;
        if (n<9){
            printf("%lu\n",n);
        }else{
           rpta=f(n);
           printf("%lu\n",rpta);
        }

    }
    return (EXIT_SUCCESS);
}