#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <set>

using namespace std;

int main() {
	int n, k;

	cin >> n >> k;

	set<int> divisor;
	for (int i = 2; i <= n / 2; i++) {
		if (n % i == 0) {
			divisor.insert(i);
			divisor.insert(n % i);
		}
	}

	int ans = 1;
	for (auto it = divisor.rbegin(); it != divisor.rend(); it++) {
		if (*it <= n / 2) {
			ans = *it;
			break;
		}
	}

	cout << ans << endl;
	return 0;
}