import java.util.*;

public class FibonacciSumLastDigit {

private static long getFibonacciSumNaive(long n) {

if (n <= 1)

return n;

long previous = 0;

long current = 1;

long sum = 1;

for (long i = 0; i < n - 1; ++i) {

long tmp_previous = previous;

previous = current;

current = tmp_previous + current;

sum += current;

}

return sum % 10;

}

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

long n = scanner.nextLong();

long s = getFibonacciSumNaive(n);

System.out.println(s);

}

}