/** * @FileName a.cpp * @Author kanpurin * @Created 2020.08.25 18:16:08 **/ #include "bits/stdc++.h" using namespace std; typedef long long ll; constexpr int MOD = 1e9 + 7; struct mint { public: long long x; mint(long long x = 0) :x((MOD+x)%MOD) {} mint(std::string &s) { long long z = 0; for (int i = 0; i < s.size(); i++) { z *= 10; z += s[i] - '0'; z %= MOD; } this->x = z; } mint& operator+=(const mint &a) { if ((x += a.x) >= MOD) x -= MOD; return *this; } mint& operator-=(const mint &a) { if ((x += MOD - a.x) >= MOD) x -= MOD; return *this; } mint& operator*=(const mint &a) { (x *= a.x) %= MOD; return *this; } mint& operator/=(const mint &a) { long long n = MOD - 2; mint u = 1, b = a; while (n > 0) { if (n & 1) { u *= b; } b *= b; n >>= 1; } return *this *= u; } mint operator+(const mint &a) const { mint res(*this); return res += a; } mint operator-(const mint &a) const { mint res(*this); return res -= a; } mint operator*(const mint &a) const { mint res(*this); return res *= a; } mint operator/(const mint &a) const { mint res(*this); return res /= a; } friend std::ostream& operator<<(std::ostream &os, const mint &n) { return os << n.x; } bool operator==(const mint &a) const { return this->x == a.x; } }; int main() { int n;cin >> n; vector a(100,0); for (int i = 0; i < n; i++) { int t;cin >> t; t--; a[t]++; } vector dp(4,0); dp[0] = 1; for (int i = 0; i < 100; i++) { if (a[i] == 0) continue; for (int j = 3; j >= 1; j--) { dp[j] += dp[j-1] * a[i]; } } cout << dp[3] << endl; return 0; }