#include <stdio.h>

int main(void){
char S[10];
	int i,c = 0;
	int suzi = atoi(S);
	
	scanf("%s", S);
	for (i = 0; S[i] != 0; i++) {
		if (S[i] == '0') {
			suzi = 10;
		}else{
			suzi = S[i] - '0';
		}
		c = c + suzi;
	}
	printf("%d\n", c); 
}