#include<stdio.h>
int main(){
	char s[10000];
	scanf("%s", &s);
	int i, sum, strLen = sizeof(s) / sizeof(s[0]);
	for(i = 0 ; i < strLen ; i++){
		if( (0x31 <= s[i]) && (s[i] <= 0x39) ){
			sum += (s[i]-0x30);
		}
	}
	printf("%d", sum);
	return 0;
}