#include <bits/stdc++.h>
using namespace std;

using std::cin;
using std::cout;

#define rep(i,n) for(int i = 0; i < (int)n; i++)
#define FOR(n) for(int i = 0; i < (int)n; i++)
#define repi(i,a,b) for(int i = (int)a; i < (int)b; i++)
#define all(x) x.begin(),x.end()
//#define mp make_pair
#define vi vector<int>
#define vvi vector<vi>
#define vvvi vector<vvi>
#define vvvvi vector<vvvi>
#define pii pair<int,int>
#define vpii vector<pair<int,int>>

template<typename T>
bool chmax(T &a, const T b) {if(a<b) {a=b; return true;} else {return false;}}
template<typename T>
bool chmin(T &a, const T b) {if(a>b) {a=b; return true;} else {return false;}}

using ll = long long;
using ld = long double;
using ull = unsigned long long;

const ll INF = numeric_limits<long long>::max() / 2;
const ld pi = 3.1415926535897932384626433832795028;
const ll mod = 1e9 + 7;
int dx[] = {1, 0, -1, 0, -1, -1, 1, 1};
int dy[] = {0, 1, 0, -1, -1, 1, -1, 1};

#define int long long

template<typename T_VAL, typename T_EXP>
T_VAL modpow(T_VAL n, T_EXP m, const T_VAL MOD) {
    // // basically (default), 0^0=1
    // // 0^0 = 0にしたいなら以下の行が必要
    // if(n == 0) return 0;
    T_VAL res = 1;
    while(m > 0) {
        if(m&1) res = (res*n)%MOD;
        n = (n*n)%MOD;
        m >>= 1;
    }
    return res;
}

void solve() {
    // gcdがbの倍数だと困る
    int a = 99990, b = 99991;
    cout << a << " " << b << endl;
    cout << flush;
    int k;
    cin >> k;
    // x = 9991の時だけやばい？
    cout << modpow(k, a, b) << endl;

    int ret;
    cin >> ret;
    assert(ret == 1);
}

int find() {
    for (int i = 100000; i >= 100; i--) {
        bool flg = true;
        repi(j, 1, i) {
            if (modpow(j, i-1, i) != 1) {
                flg = false;
                break;
            }
        }
        cerr << "TEST: " << i << endl;
        if (flg && modpow(i-1, i, mod) == i) return i;
    }
}

signed main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << find() << endl;
    // solve();
    return 0;
}