#include <bits/stdc++.h>
using namespace std;
#define int long long   // <-----!!!!!!!!!!!!!!!!!!!

#define rep(i,n) for (int i=0;i<(n);i++)
#define rep2(i,a,b) for (int i=(a);i<(b);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
#define rrep2(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef pair<int, int> P;

int gcd(int a, int b) {
    if (b == 0) return a;
    return gcd(b, a % b);
}

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int n, k;
    cin >> n >> k;
    int ans = 0;
    rep2(i, 1, n) {
        ans = max(ans, gcd(i, n - i));
    }
    cout << ans << endl;
}