#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    ll L, R, C;
    cin >> L >> R >> C;
    vector<bool> seen(1000);
    ll ans = 1000;
    ll now = C * L % 1000;
    for (ll i = L; i <= R; i++) {
        if (seen[now]) break;
        seen[now] = true;
        if (now == 0) {
            ans = 0;
        } else {
            ans = min(ans, 1000 - now);
        }
        now += C;
        now %= 1000;
    }
    cout << ans << endl;
    return 0;
}