#include<iostream>
usi#ng namespace std;
int main(){
    int n,g,s,b;
    cin>>n;
    b=n/100;
    g=n%10;
    s=n/10%10;
    cout<<(b+s+g)<<endl;
    return 0;
}
/**************************************************************
	Problem: 1027
	User: chenmingyu
	Language: C++
	Result: Compile Error
****************************************************************/