题目描述

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输入格式

As shown in the PDF.

输出格式

As shown in the PDF

样例

7 
6 2 4 
2 3 1 
2 4 10 
5 3 4 
1 3 2 
2 5 4 
4 3 2

8 
-1 
-1 
-1 
4 
1 
-1

提示

Note In the first test case, there's a desired circle of 8 people. The person with the number 6 will look at the person with the number 2 and the person with the number 8 will look at the person with the number 4.

In the second test case, there's no circle meeting the conditions. If the person with the number 2 is looking at the person with the number 3, the circle consists of 2 people because these persons are neighbors. But, in this case, they must have the numbers 1 and 2, but it doesn't meet the problem's conditions.

In the third test case, the only circle with the persons with the numbers 2 and 4 looking at each other consists of 4 people. Therefore, the person with the number 10 doesn't occur in the circle.

Codeforces Round #739 (Div. 3) B题

Input by QLU_张席畅