#include <iostream>
#include <set>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
  long long l,r,c;cin>>l>>r>>c;
  set<int> A;
  vector<int> B;
  long long nw = ((l-1)*c)%1000;
  for(int i = l; r >= i; i++){
    nw = (nw+c)%1000;
    long long rem = (1000-nw)%1000;
    if(A.count(rem)){
      sort(B.begin(),B.end());
      cout << B[0] << endl;
      return 0;
    }
    A.insert(rem);
    B.push_back(rem);
  }
  sort(B.begin(), B.end());
  cout << B[0] << endl;
}