#include <stdio.h>
using namespace std; 
int main() {
    int w;
    scanf("%d", &w);
    printf("%d", w/100 + (w/10)%10 + w%10);
    return 0;
}
/**************************************************************
	Problem: 1716
	User: zhangyilei
	Language: C++
	Result: Accepted
	Time:21 ms
	Memory:1144 kb
****************************************************************/