#include <iostream>
using namespace std;

int main()
{
    int L, R, C, A;
    A = 1000;
    cin >> L >> R >> C;
    int l = L - L / 1000*1000;
    int r = R - R / 1000 * 1000;
    int c = C - C / 1000*1000;
    if (R - L > 1000) {
        r = l + 999;
    }
    else {
        r = l + (R - L);
    }
    for (int i = l; i < r+1; i++) {
        if (A > ((i * c - 1) / 1000 + 1) * 1000 - i * c) {
            A = ((i * c - 1) / 1000 + 1) * 1000 - i * c;
        }
        //cout << l << " " << c << " " << ((i * c - 1) / 1000 + 1) << " " << A << endl;
    }
    if (A == 1000) {
        A = 0;
    }
    cout << A << endl;
    return 0;
}