A了

#include <bits/stdc++.h>

using namespace std;

int main() {
    long long n;

    cin >> n;

    long long sum = 1;

    for (long long i = 1; i <= n; ++i) {
        if (sum > sum % 1000003) {
            sum = sum % 1000003;
        }
        sum *= i;
    }

    cout << (sum % 1000003) << endl;
}