题解

#include <bits/stdc++.h>
using namespace std;

int main() {
	int t,n,f;
	cin >> t;
	for (int i=1;i<=t;i++){
		cin >> n;
		int a[1010] = {0};
		for (int i = 1; i <= n; i++) {
			cin >> f;
			a[f] = i;
		}
		int cnt = -1;
		for (int i = 1; i <= 1000; i++) {
			for (int j = i; j <= 1000; j++) {
					if (a[i] && a[j] && __gcd(i,j)==1 && a[i]+a[j]>cnt) cnt=a[i]+a[j];
			}
		}
		cout << cnt << "\n";
	}
	return 0;
}