#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
long long primeNumber(long long x) {
  bool fire = true;
  for(int i = 2; i <= sqrt(x); i++) {
    if(x % i == 0) {
      fire = false;
    }
  }
  return fire;
}
int main() {
  long long L,R,C; cin >> L >> R >> C;
  long long ans = 1ll << 60ll;
  int count = 0;
  for(int i = L; i <= R; i++) {
    long long X = i * C;
    long long A = 1000 - (X % 1000);
    ans = min(ans,A);
    count++;
    if(count >= 1500) {
      break;
    }
  }
  cout << ans << endl;
}