hdu 1013(模拟)

//模拟，注意题中没有给出数据的大小
#include <cstdio>
#include <cstring>
#include <iostream>

using namespace std;

char n[1005];

int solve() {
int sum = 0;
int l = strlen(n);
for (int i=0; i<l; ++i) sum += n[i] - '0';
if (sum > 9) {
int s, m;
        s = m = sum;
        sum = 0;
while (s > 9) {
while (m) {
                sum += m % 10;
                m /= 10;
            }
            s = m = sum;
if (sum >= 10) sum = 0;
        }
    }
return sum;
}

int main() {
while (scanf("%s", n), strcmp(n, "0")!=0) {
int sum = solve();
        printf ("%d\n", sum);
    }
return 0;
}