#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,s,a,b,c;
    scanf("%d",&x);
    a=x%10;
    b=x/10%10;
    c=x/100;
    s=a+b+c;
    printf("%d",s);
     
}
/**************************************************************
	Problem: 1027
	User: zhangyilei
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2076 kb
****************************************************************/