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

int main(void) {
	int sum=0,i,l;
	char s[16384];
	scanf("%s",s);
	l = strlen(s);
	for(i = 0;i < l;i++){
		if(s[i] == '1'){sum+=1;}
		if(s[i] == '2'){sum+=2;}
		if(s[i] == '3'){sum+=3;}
		if(s[i] == '4'){sum+=4;}
		if(s[i] == '5'){sum+=5;}
		if(s[i] == '6'){sum+=6;}
		if(s[i] == '7'){sum+=7;}
		if(s[i] == '8'){sum+=8;}
		if(s[i] == '9'){sum+=9;}
	}
	printf("%d\n",sum);
	return 0;
}