#include <stdio.h>
#include<string.h>
int main()
{
	char s[200];
	gets(s);
	int i=0,j,m=strlen(s);
		for(j=0;j<m;j++){
  	i=i+s[j]-48;	
	}
printf("%d ",i);
	return 0;
}


/**************************************************************
	Problem: 1115
	User: admin
	Language: C
	Result: Accepted
	Time:9 ms
	Memory:1036 kb
****************************************************************/