#include <bits/stdc++.h>
using namespace std;
long long int modulo = 1e9 + 7;
int n;
vector<vector<long long int> > cero, identidad;
vector<vector<long long int> > operator*(vector<vector<long long int> > m1,
                                         vector<vector<long long int> > m2) {
  vector<vector<long long int> > m(n, vector<long long int>(n, 0));
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      for (int k = 0; k < n; k++)
        m[i][j] = (m[i][j] + m1[i][k] * m2[k][j]) % modulo;
  return m;
}
vector<long long int> operator*(vector<vector<long long int> > m,
                                vector<long long int> v) {
  vector<long long int> r(n, 0);
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) r[i] = (r[i] + m[i][j] * v[j]) % modulo;
  return r;
}
vector<vector<long long int> > s[50];
int main() {
  long long int x;
  int b;
  cin >> x >> b;
  x--;
  n = b + 1;
  identidad = cero =
      vector<vector<long long int> >(n, vector<long long int>(n, 0));
  for (int i = 0; i < n; i++) identidad[i][i] = 1;
  s[0] = identidad;
  s[1] = cero;
  for (int i = 0; i < n - 2; i++) s[1][i][i + 1] = 1;
  s[1][n - 2][0] = 1;
  s[1][n - 1][n - 1] = 1;
  for (int i = 2; i <= b - 1; i++) s[i] = s[1] * s[i - 1];
  vector<vector<long long int> > N = identidad;
  N[0][0] = 0;
  N[0][n - 1] = 1;
  N[n - 1][0] = -1;
  N[n - 1][n - 1] = 2;
  vector<vector<long long int> > M = N;
  while (x) {
    int d = x % b;
    x /= b;
    vector<vector<long long int> > nextM = M;
    for (int i = 1; i < b; i++) {
      if (i == d) N = s[b - i] * N * s[i] * nextM;
      nextM = s[b - i] * M * s[i] * nextM;
    }
    M = nextM;
  }
  vector<long long int> v(n, 0);
  v[n - 1] = 1;
  long long int sol = (N * v)[n - 1];
  cout << (sol + modulo) % modulo << endl;
}
