#include <bits/stdc++.h>
using namespace std;
using ch = char;
using ll = long long;
using ld = long double;
using db = double;
using st = string;
using vdb = vector<db>;
using vvdb = vector<vdb>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<ld>;
using vvd = vector<vd>;
using vs = vector<st>;
using vvs = vector<vs>;
using vc = vector<ch>;
using vvc = vector<vc>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvvb = vector<vvb>;
const ll mod = 998244353;
const ll MOD = 1000000007;
const ll INF = 1000000000000000000LL;
using pall = pair<ll,ll>;
using vp = vector<pall>;

int main(){
    ll L,R,C;
    cin>>L>>R>>C;
    set<ll> X;
    for(ll i=L; i<=R; i++){
        if(!X.count((1000 - i*C%1000)%1000)){
            X.insert((1000 - i*C%1000)%1000);
        }
        else{
            break;
        }
    }
    cout << *X.begin() << endl;
}