#include <stdio.h>
int main(){
    int n;
    int m = 0;//有必要对m做初始化,否则m += n % 10;会把m随机值计入
    scanf("%d",&n);
    while(n > 0){
        m += n % 10; 
        n = n/10;    
    }
    printf("%d",m);
    return 0;
}