#include<bits/stdc++.h>
using namespace std;
int main(){
    char a[205]; 
    cin>>a;
    int s=0;
    for(int i=0;i<strlen(a);i++){
        s=s+(a[i]-'0');
    }
    cout<<s<<endl;
    return 0;
}
/**************************************************************
	Problem: 1115
	User: luyanchen
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/