#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < (n); i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = 1001001001;
const ll LINF = 1001002003004005006ll;
//const int mod = 1000000007;
//const int mod = 998244353;

int main()
{
  ll l, r, c;
  cin >> l >> r >> c;
  map<ll, ll> mp;
  ll ans = LINF;
  for (ll i = l; i <= r; i++) {
    if (i*c <= 1000) {
      ans = min(ans, 1000 - i*c);
    }
    else if (mp[1000-i*c%1000]) break;
    else {
      mp[1000-i*c%1000] = 1;
      ans = min(ans, 1000-i*c%1000);
    }
  }
  cout << ans << endl;
  return 0;
}