#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,i=0,a=0,c=0,m=0;
	cin>>x;
		i=x%10;
		a=x%100/10;
		c=x%1000/100;
		m=i+c;
		cout<<m;
    }

/**************************************************************
	Problem: 1614
	User: huxuanchen
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/