参考答案：

#include<iostream>
using namespace std;
const int N = 100010;
int a[N];
int sum, n;
int b;
int main()
{
    cin >> n;
    for (int i = 1; i <= n; ++i) cin >> a[i];
    cin >> b;
    for (int i = 1; i <= n; ++i)
    {
        if (b + 30 >= a[i]) sum++;
    }
    cout << sum << endl;
    return 0;
}