#include <bits/stdc++.h>
using namespace std;
string to_string(string s) { return '"' + s + '"'; }
string to_string(const char *s) { return to_string((string)s); }
string to_string(bool b) { return (b ? "true" : "false"); }
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> t) {
  return "(" + to_string(get<0>(t)) + ", " + to_string(get<1>(t)) + ", " +
         to_string(get<2>(t)) + ")";
}
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += '}';
  return res;
}
void _debug() { cerr << '\n'; }
template <typename Head, typename... Tail>
void _debug(Head H, Tail... T) {
  cerr << ' ' << to_string(H);
  _debug(T...);
}
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using vi = vector<int>;
using vii = vector<ii>;
using vc = vector<char>;
using vb = vector<bool>;
int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(9);
  int n, k;
  cin >> n >> k;
  int lo = 1, hi = n;
  while (lo < hi) {
    int mid = lo + (hi - lo) / 2;
    int total = 0;
    int cur = mid;
    while (cur) {
      total += cur;
      cur /= k;
    }
    if (total >= n) {
      hi = mid;
    } else {
      lo = mid + 1;
    }
  }
  cout << hi;
}
