#include <iostream>

using namespace std;

void loadData(int n, int * arr) {

    for (int i=0; i<n; i++) cin >> arr[i];

}

int main() {

    int * data, n, num_kayaks = 0;

    cin >> n;

    data = new int;

    loadData(n, data);

    for (int i=0; i<n/2+1; i++) {

        if (data[i] + data[n-i-1] <= 120) num_kayaks += 1;

        else num_kayaks += 2;

    }

    cout << num_kayaks;

    return 0;

}