#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() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
long long int power(long long int x, long long int y) {
  long long int ans = 1;
  x %= 1000000007;
  while (y) {
    if (y & 1) ans = (x * ans) % 1000000007;
    x = (x * x) % 1000000007;
    y >>= 1;
  }
  return ans;
}
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
void solve() {
  long long int n, k;
  cin >> n >> k;
  long long int lo = 0;
  long long int hi = n + 1;
  while (lo < hi) {
    long long int mid = (lo + hi) >> 1;
    long long int v = mid;
    long long int sum = v;
    long long int curr = k;
    while (true) {
      long long int toAdd = v / curr;
      if (!toAdd) break;
      sum += toAdd;
      curr *= k;
    }
    if (sum < n) {
      lo = mid + 1;
    } else {
      hi = mid;
    }
  }
  cout << lo << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
}
