TaskI

#include <iostream>

using namespace std;

int main()
{
    int n, res = 0;
    cin >> n;
    int* numbers = new int[n];
    for (int i = 0; i < n; i++)
        cin >> numbers[i];
    for (int i = 0; i < n - 1; i++)
        if ((i + 1) % 2 == 0 && numbers[i + 1] - numbers[i] >= 3)
            res++;
    cout << res << endl;
}