#include <iostream>
#include <string>
#include <numeric>
using namespace std;

int calculateSuperDigit(long long num) {
    if (num < 10) {
        return static_cast<int>(num);
    }

    long long sum_of_digits = 0;
    while (num > 0) {
        sum_of_digits += num % 10; 
        num /= 10;                 
    }

    return calculateSuperDigit(sum_of_digits);
}

int superDigit(string n, int k) {
    long long sum_n = 0;
    for (char c : n) {
        sum_n += c - '0'; 
    }

  
    long long initial_sum = sum_n * k;

    return calculateSuperDigit(initial_sum);
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    string n;
    int k;

    cin >> n >> k;

    int result = superDigit(n, k);

    cout << result << endl;

    return 0;
}