#include <stdio.h>

int main()
{
	int num;

	int box = 0;

	int i; 

	scanf("%d", &num);

	if((0 <= num ) && (num < 10))
	{
		printf("%d\n", num);
		return 0;
	}
	else if((10 <= num ) && (num < 100))
	{
		box = (num / 10);
		box = box + (num % 10);
		printf("%d\n", box);
		return 0;
	}
	else if((100 <= num) && (num < 1000))
	{
		box = (num / 100);
		box = box + ((num % 100) / 10);
		box = box + (num % 10);
		printf("%d\n", box);
		return 0;
	}
	else if((1000 <= num) && (num < 10000))
	{
		box = num / 1000;
		box = box + ((num % 1000) / 100);
		box = box + ((num % 100) / 10);
		box = box + (num % 10);
		printf("%d\n", box);
		return 0;
	}
	else if((10000 <= num) && (num < 100000))
	{
		box = num / 10000;
		box = box + ((num % 10000) / 1000);
		box = box + ((num % 1000) / 100);
		box = box + ((num % 100) / 10);
		box = box + (num % 10);
		printf("%d\n", box);
		return 0;
	}
	else if((100000 <= num) && (num < 1000000))
	{
		box = num / 100000;
		box = box + ((num % 100000) / 10000);
		box = box + ((num % 10000) / 1000);
		box = box + ((num % 1000) / 100);
		box = box + ((num % 100) / 10);
		box = box + (num % 10);
		printf("%d\n", box);
		return 0;
	}
	else if((1000000 <= num) && (num < 10000000))
	{
		box = num / 1000000;
		box = box + ((num % 1000000) / 100000);
		box = box + ((num % 100000) / 10000);
		box = box + ((num % 10000) / 1000);
		box = box + ((num % 1000) / 100);
		box = box + ((num % 100) / 10);
		box = box + (num % 10);
		printf("%d\n", box);
		return 0;
	}
	else if((10000000 <= num) && (num < 100000000))
	{
		box = num / 10000000;
		box = box + ((num % 10000000) / 1000000);
		box = box + ((num % 1000000) / 100000);
		box = box + ((num % 100000) / 10000);
		box = box + ((num % 10000) / 1000);
		box = box + ((num % 1000) / 100);
		box = box + ((num % 100) / 10);
		box = box + (num % 10);
		printf("%d\n", box);
		return 0;
	}
	else if((100000000 <= num) && (num < 1000000000))
	{
		box = num / 100000000;
		box = box + ((num % 100000000) / 10000000);
		box = box + ((num % 10000000) / 1000000);
		box = box + ((num % 1000000) / 100000);
		box = box + ((num % 100000) / 10000);
		box = box + ((num % 10000) / 1000);
		box = box + ((num % 1000) / 100);
		box = box + ((num % 100) / 10);
		box = box + ((num % 10));
		printf("%d\n", box);
		return 0;
	}
	else if(num == 1000000000)
	{
		box = num / 1000000000;
		box = num + ((num % 1000000000) / 100000000);
		box = num + ((num % 100000000) / 10000000);
		box = num + ((num % 10000000) / 1000000);
		box = num + ((num % 1000000) / 100000);
		box = num + ((num % 100000) / 10000);
		box = num + ((num % 10000) / 1000);
		box = num + ((num % 1000) / 100);
		box = num + ((num % 100) / 10);
		box = num + (num % 10);
		printf("%d\n", box);
		return 0;
	}

	return 0;
}