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

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

// std::vector Declaration
template<typename T>
vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T, typename... Ts>
auto make_v(size_t a, Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}

// std::vector Declaration and Initialization
template<typename T>
vector<T> make_vector(size_t a, T x) { return vector<T>(a, x); }
template<typename T, typename U, typename... Ts>
auto make_vector(size_t a, U b, Ts... ts) {
    return vector<decltype(make_vector<T>(b,ts...))>(a, make_vector<T>(b, ts...));
}

// std::vector Input
template<typename T>
istream& operator>>(istream& is, vector<T>& v) {
    for (auto &e : v) is >> e;
    return is;
}

// std::vector Debug
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::array Debug
template<typename T, size_t n>
ostream& operator<<(ostream& os, const array<T, n>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::deque Debug
template<typename T>
ostream& operator<<(ostream& os, const deque<T>& d) {
    os << "[";
    bool a = 1;
    for (auto e : d) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::pair Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << "(" << p.first << " " << p.second << ")";
    return os;
}

// std::set Debug
template<typename T>
ostream& operator<<(ostream& os, const set<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::multiset Debug
template<typename T>
ostream& operator<<(ostream& os, const multiset<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::map Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const map<T, U>& mp) {
    os << "{";
    bool a = 1;
    for (auto e : mp) {
        os << (a ? "" : " ");
        os << e.first << ":" << e.second;
        a = 0;
    }
    os << "}";
    return os;
}

// std::tuple Debug
template<int N, class Tuple>
void out(ostream& os, const Tuple& t){}
template<int N, class Tuple, class H, class ...Ts>
void out(ostream& os, const Tuple& t) {
    if (N) os << " ";
    os << get<N>(t);
    out<N+1,Tuple,Ts...>(os, t);
}
template<class ...Ts>
ostream& operator<<(ostream& os, const tuple<Ts...>& t) {
    os << "(";
    out<0,tuple<Ts...>,Ts...>(os, t);
    os << ")";
    return os;
}

// Debug
#define DUMP(x) cerr<<#x<<" = "<<(x)<<endl

// Weighted edge
template<typename T>
struct edge {
    int src, to;
    T cost;

    edge() {}
    edge(int to, T cost) : src(-1), to(to), cost(cost) {}
    edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

    friend ostream& operator<<(ostream& os, const edge& e) {
        return os << "(" << e.src << "->" << e.to << ":" << e.cost << ")";
    }
};

using LL = int64_t;

#define fs first
#define sc second

const int64_t MOD = 1e9+7;

// O(sqrt(N))
int64_t euler_phi(int64_t n) {
    int64_t ret = n;
    for (int64_t i = 2; i * i <= n; ++i) {
        if (n % i != 0) continue;
        ret -= ret / i;
        while (n % i == 0) n /= i;
    }
    if (n > 1) ret -= ret / n;
    return ret;
}

int64_t powmod(int64_t a, int64_t n, int64_t mod) {
    int64_t ret = 1, tmp = a;
    while (n) {
        if (n & 1) (ret *= tmp) %= mod;
        (tmp *= tmp) %= mod;
        n >>= 1;
    }
    return ret;
}


int64_t __lcm(int64_t a, int64_t b) {
    return a / __gcd(a, b) * b;
}

// O(sqrt(n))
map<int64_t, int> prime_factorize(int64_t n) {
    map<int64_t, int> ret;
    for (int64_t i = 2; i * i <= n; i++) {
        while (n % i == 0) {
            ret[i]++;
            n /= i;
        }
    }
    if (n != 1) ret[n] = 1;
    return ret;
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    LL n; cin >> n;

    auto fact = prime_factorize(n);

    if (fact.size() == 1 and fact.begin()->second == 1) {
        cout << 1 << endl;
        return 0;
    }

    vector<int> primes;
    for (const auto& tp : fact) {
        if (tp.second > 1) {
            cout << -1 << endl;
            return 0;
        }
        primes.push_back(tp.first);
    }

    LL lcm = 1;
    for (LL p : primes) {
        lcm = __lcm(lcm, p-1);
    }

    if (__gcd(n, lcm) != 1) {
        cout << -1 << endl;
        return 0;
    }

    LL phi = euler_phi(lcm);

    LL ans = numeric_limits<LL>::max();
    for (LL i = 1; i * i <= phi; ++i) {
        if (phi % i != 0) continue;
        if (powmod(n, i, lcm) == 1) chmin(ans, i);
        if (powmod(n, phi / i, lcm) == 1) chmin(ans, phi / i);
    }

    cout << ans << endl;

    return 0;
}



Measured memory_bytes: 3236