#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

const int mod = 1000000007;

int main() {
    int n;
    cin >> n;
    int x;
    vector<int> data(n);
    for(int i=0;i<n;i++)
        {
        cin>>data[i];
        }
    sort(data.begin(),data.end());
    int ans = 1;
    for(int i = 1; i < n; i++)
        {
        if(data[i] == data[i-1])
            {
            ans = (ans+ans-1)%mod;
            }
        else
            {
            ans = (ans * 2) % mod;
            }
        }
    cout << ans;
    return 0;
}