#include <fstream>
#include <cstdio>
#include <string>

int cifra(const std::string& buffer) {
	const int partialSum[] = {
		1, 5, 2, 8, 3, 9, 2, 8, 7, 7
	};
	const int size = buffer.size();
	int result = 0;
	
	if (size > 0)
		result = partialSum[(buffer[size - 1] - '0' + 9) % 10];
	
	if (size > 1)
		result += (buffer[size - 2] - '0') * partialSum[9];
	
	return result % 10;
}

int main() {
	char const * const inputFile = "cifra.in",
						 * const outputFile = "cifra.out";
	std::ifstream in(inputFile);
	std::ofstream out(outputFile);
	
	std::string buffer;
	std::getline(in, buffer);
	while (std::getline(in, buffer))
		out << cifra(buffer) << std::endl;
	return 0;
}