#include<stdio.h>
int main() {
    int n;
    int sum = 0;
    scanf("%d", &n);
    if (n<0) {
    n=0-n;
    }
    while (n!=0) {
        sum += n % 10;
        n = n / 10;
    }
    printf("%d", sum);
    return 0;
}