#include <stdio.h>
 
int main(void) {
	int n;
	scanf("%d", &n);
	for (int count = 0; count < n; count++) {
		int len;
		scanf("%d", &len);
		int data[5050];
		for (int i = 0; i < len; i++) {
			scanf("%d", &data[i]);
		}
		int flag = 0;
		for (int i = 0; i < len-2; i++) {
			for (int j = 2; j < len-i; j++) {
				// from i to i + j
				int times = (j + 1) / 2;
				int flag2 = 0;
				for (int k = 0; k < times; k++) {
					flag2 = 1;
					if (data[i+k]!=data[i+j-k]) {
						flag2 = 0;
						break;
					}
				}
				if (flag2) {
					flag = 1;
				}
			}
		}
		if (flag) {
			printf("YES\n");
		}else {
			printf("NO\n");
		}
	}
	return 0;
}
 

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3
1 2 1
5
1 2 2 3 2
3
1 1 2
4
1 2 2 1
10
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