#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin >> n;
    
    vector<int> arr(n);
    
    for(int i=0;i<n;i++)
    cin >> arr[i];
    
    int jump = 0;
    
    for(int i=0;i<n;i++)
    {
        if(i>jump)
        {
            cout<<"False";
            return;
        }
        jump = max (jump,i+arr[i]);
    }
    cout<<"True";
}