#include <iostream>
#define MOD 1000000007
#define ull unsigned long long
#include<map>
using namespace std;

ull logpow(ull b, ull p){
    if(p==0)
        return 1LL;
    if(p==1)
        return b;

    ull x = logpow(b, p/2);
    if(p%2==0){
        return (x*x)%MOD;
    }
    else
        return ((x*x)%MOD*b)%MOD;
}


ull fact[300200];

ull comb(int b, int a){
    return ((( fact[b] * logpow(fact[a], MOD-2))%MOD * logpow(fact[b-a], MOD-2))   %MOD)%MOD;
}


int main()
{
    int n;
    cin>>n;

    fact[0]=1LL;
    for(int i=1; i<=2*n; i++){
        fact[i] = ((fact[i-1])*i)%MOD;
    }


    map<int, int> freqs;

    int x;
    for(int i=0; i<n; i++){
        cin>>x;
        freqs[x]++;
    }

    ull sol=1;

    for(auto p:freqs){
        sol = (sol * comb(2*p.second, p.second) )%MOD;
    }

    sol = (sol+MOD-1)%MOD;

    cout<<sol;
    return 0;
}