#include <stdio.h>
#include <string.h>

int main(){
	char S[10000] = {'\0'};
	int i, sum = 0;
	scanf("%s", S);
	for(i = 0; i < strlen(S); i++){
		if(S[i] >= '0' && S[i] <= '9') sum += (int)(S[i] - '0');
	}
	printf("%d\n", sum);
	return 0;
}