#include <bits/stdc++.h>
using namespace std;

int main()
{
    int l, n;
    cin >> l >> n;
    int num = pow(26, l) - n;
    char a[l];
    for (int i = l - 1; i >= 0; i--)
        a[i] = num % 26 + 'a', num /= 26;
    for (auto c : a) cout << c;
    return 0;
}