#include <fstream>
#include <string>
 
const int partialSum[] = {
    0, 1, 5, 2, 8, 3, 9, 2, 8, 7, 7, 8, 4, 7, 3, 8, 4, 1, 5, 4
};
  
int main() {
    char const * const inputFile = "cifra.in",
                         * const outputFile = "cifra.out";
    std::ifstream in(inputFile);
    std::ofstream out(outputFile);
     
    std::string buffer;
    buffer.reserve(128);
    in >> buffer;
     
    while (in >> buffer) 
        if (!buffer.empty()) {
            int size = buffer.size(), n = buffer[size - 1] - '0';
            if (size > 1)
                n += 10 * (buffer[size - 2] - '0');
            out << ((partialSum[n % 20] + 4 * (n / 20)) % 10) << std::endl;
        }
    return 0;
}