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

int main()
{
	int n; cin >> n;
	int a[n];
	for(int i=0; i<n; i++) cin >> a[i];
	sort(a, a+n);
	
	
	if(a[0]!=1)
	{
		cout << 0;
	}
	else
	{
		vector<pair<int,int> > k;
		k.push_back(make_pair(0,1));
		int ans = 0;
		while(k.size()>0)
		{
			pair<int,int> x = k.back();
			
			ans = (ans+1)%1000000007;
			k.pop_back();
			for(int i=x.first+1;i<n;i++)
			{
				if(a[i]<=x.second+1)
				{
					k.push_back(make_pair(i,x.second+a[i]));
				}
				else break;
			}
		}
		cout << ans;
	}
	
	
	
	
	
	
	return 0;
}