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

int main() {
    int n = 0;
    int sum = 0;
    int num = 0;
    scanf("%d",&n);
    if (n < 0) {
       n  = abs(n);
    }
    while (n != 0) {
        num = n % 10;
        sum += num;
        n /= 10;
    }
    printf("%d",sum);
    return 0;
}