#include <stdio.h>

#define MAX 1000

int main()
{
	int times, i,j;
	char numbers[MAX + 1];

	scanf("%d%*c", &times);

	for (i = 0;i < times;i++) {
		fgets(numbers, MAX + 1, stdin);
		
		for (j = 0;numbers[j] != '\n';j++);
		numbers[j] = '\0';

		while (numbers[1] != '\0') {
			for (j = 0;numbers[j + 1] != '\0';j++) {
				numbers[j] += numbers[j + 1] - '0';
				if (numbers[j] >= ':') {
					numbers[j] -= 9;
				}
			}
			numbers[j] = '\0';
		}

		printf("%c\n", numbers[0]);
	}

	return 0;
}