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

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return std::vector(arg, init);
    else return std::vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

#include <boost/multiprecision/cpp_int.hpp>
using bint = boost::multiprecision::cpp_int;

#include <atcoder/modint>
using mint = atcoder::modint1000000007;

int main() {
    int a; cin >> a;

    auto b = [&] {
        string s; cin >> s;

        bint b = 0;
        for (auto c : s) {
            b *= a;
            b += c - '0';
        }

        return b;
    }();

    mint ans = 0;

    bint k = 1;
    for (int i = 0; k <= b; ++i) {
        if (b < k * a) {
            ans += int((i * (b - k + 1)) % mint::mod());
        }
        else {
            ans += i * mint(a).pow(i) * (a - 1);
        }
        k *= a;
    }

    cout << ans.val() << endl;
}