#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void __print(vector<bool> x) {
  cerr << "{";
  int f = x.size();
  for (auto i : x) {
    cerr << i;
    (--f != 0) ? cerr << "," : cerr << "";
  }
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
template <typename... T>
void read(T &...args) {
  ((cin >> args), ...);
}
template <typename... T>
void writ(T &&...args) {
  ((cout << args << " "), ...);
}
long long func1(long long n, long long k) {
  long long an = 0, r = 1;
  while (n / r) {
    an += n / r;
    r *= k;
  }
  return an;
}
long long binse(long long n, long long k) {
  long long st = 1, en = n, an;
  while (st <= en) {
    long long mid = (st + en) / 2;
    long long v = func1(mid, k);
    ;
    if (v >= n) {
      an = mid;
      en = mid - 1;
    } else {
      st = mid + 1;
    }
  }
  return an;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, k;
  cin >> n >> k;
  cout << binse(n, k);
  return 0;
}
