WA 1 2 9 10，求问错哪了，对照输出看了很久，感觉没有问题

#include<iostream>
using namespace std;
int a[5] = { -1,-1,1,7,4};
int b[7] = { 2,6,8,10,18,200,20};
int main() {
	int T;
	cin >> T;
	for (int i = 1; i <= T; i++) {
		int n;
		//cin >> n;
		n = i;
		if (n <= 4)cout << a[i];
		else if (n == 10)cout << 22;
		else {
			cout << b[(n - 5) % 7];
			int k = (n - 5) / 7;
			if ((n - 5) % 7 == 5)k--;
			for (int j = 1; j <= k; j++)cout << 8;
		}
		cout << endl;
	}
	return 0;
}