#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i = 0; i < n; i++)
#define repr(i, n) for(int i = n; i >= 0; i--)
#define range(i, m, n) for(int i = m; i < n; i++)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
#define sum(v) accumulate(ALL(v),0)
#define int long long
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll INF = 1e16;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
using Graph = vector<vector<ll>>;
int32_t main(){
    int N;cin >> N;
    vl A(N,0);
    rep(i,N)cin >> A[i];
    sort(ALL(A));
    vl Fact(21,1);
    range(i,2,21)Fact[i] = i*Fact[i-1];
    //cout << Fact[20] << endl;
    int Same=1;
    int Ans = Fact[N];
    range(i,1,N){
        if(A[i]!=A[i-1]){
            Ans/=Fact[Same];
            Same = 1;
        }
        else Same+=1;
    }
    Ans/=Fact[Same];
    cout << Ans << endl;
}