#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using tlll = tuple<ll, ll, ll>;
constexpr ll MOD = 1e9 + 7;
//constexpr ll MOD = 998244353;
//constexpr ll MOD = ;
ll mod(ll A, ll M) {return (A % M + M) % M;}
constexpr ll INF = 1LL << 60;
template<class T> bool chmin(T& a, T b) {if (a > b) {a = b; return true;} return false;}
template<class T> bool chmax(T& a, T b) {if (a < b) {a = b; return true;} return false;}
ll divceil(ll A, ll B) {return (A + (B - 1)) / B;}
#define FINALANS(A) do {cout << (A) << '\n'; exit(0);} while (false)

int main()
{
  ll A;
  string B;
  cin >> A >> B;

  ll L = B.size();

  ll ans1 = 0;
  for (ll l = 0, dig = 1; l < L - 1; l++, dig *= A, dig %= MOD)
  {
    ll tmp = l * (A - 1) % MOD * dig % MOD;
    ans1 += tmp, ans1 %= MOD;
  }

  ll ans2 = 0;
  for (ll l = L - 1, dig = 1; l >= 0; l--, dig *= A, dig %= MOD)
  {
    ll c = B.at(l) - '0';
    if (l == L - 1)
      c++;
    if (l == 0)
      c--;

    ll tmp = (L - 1) * c % MOD * dig % MOD;
    ans2 += tmp, ans2 %= MOD;

    //cerr << tmp << endl;
  }

  ll ans = (ans1 + ans2) % MOD;
  cout << ans << endl;

  //cerr << ans1 << " " << ans2 << endl;
}