#include<iostream>
#include<vector>
using namespace std;
main()
{
    int N;
    cin>>N;
    vector<int>A(N);
    for(int i=0;i<N;i++)cin>>A[i];
    while(A.size()>1)
    {
        vector<int>B(A.size()-1);
        for(int i=0;i<B.size();i++)B[i]=(A[i]+A[i+1])%1000000007;
        A=B;
    }
    cout<<A[0]<<endl;
}