#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: toughuatao1
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2076 kb
****************************************************************/