#include <iostream>
#include <string>
using namespace std;
 
int recursiveDigitSum(string n)
{
    int sum = 0;
    for (int i = 0; i < n.length(); i++)
    {
        sum += (n[i]) - '0';
    }
 
    if (sum < 10)
        return sum;
 
    return recursiveDigitSum(to_string(sum));
}
 
int main()
{
    int n, k;
    cin >> n >> k;
    if (n < 10 && k == 0)
    {
        cout << n;
        return 0;
    }
 
    string s = to_string(n);
    long long sumDigits = 0;
    for (char c : s)
        sumDigits += (c - '0');
 
    long long total = sumDigits * k;
 
    cout << recursiveDigitSum(to_string(total));
 
    return 0;
}

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