#include<stdio.h>   

int main(){  
	int x;
	scanf("%d",&x);
	
	int b = x / 100;
	int s = x / 10 % 10;
	int g = x % 10;
	
	printf("%d",b+s+g);
	
	return 0; 
} 
/**************************************************************
	Problem: 1027
	User: admin
	Language: C
	Result: Accepted
	Time:10 ms
	Memory:1144 kb
****************************************************************/