#include<bits/stdc++.h>
using namespace std;
int main(){
    int a,b,c,d;
    scanf("%d",&a);
    b=a%10;
    c=a/10%10;
    d=c+b;
    printf("%d",d);
}
/**************************************************************
	Problem: 1605
	User: xuezihong1
	Language: C++
	Result: Accepted
	Time:15 ms
	Memory:2076 kb
****************************************************************/