#include <stdio.h>

int main(void) {
	// your code goes here
	int x,a,b,c,d,sum;
	scanf("%d\n",&x);
	a=x/1000;
	b=(x-a*1000)/100;
	c=(x-a*1000-b*100)/10;
	d=x%10;
	sum=a+b+c+d;
	printf("sum=%d\n",sum);
	return 0;
}