#include<stdio.h>

int main(){
    int n,sum;
    
    scanf("%d",&n);
    
     i=n%10;
     sum=n/10;
     j=sum%10;
     
     sum3=sum/10;
     k=sum%10;
     
     int final=i+j+k;
     
    printf("%d",final);
    
    return 0;
    
}