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Problems

I Can Guess the Data Structure!

I Can Guess the Data Structure!

Time limit 1 second
Memory limit 64 MiB

There is a bag-like data structure, supporting two operations:

Given a sequence of operations with return values, you're going to guess the data structure. It is a stack (Last-In, First-Out), a queue (First-In, First-Out), a priority-queue (Always take out larger elements first) or something else that you can hardly imagine!

Input data

There are several test cases. Each test case begins with a line containing a single integer n (1n1000). Each of the next n lines is either a type-1 command, or an integer 2 followed by an integer x. That means after executing a type-2 command, we get an element x without error. The value of x is always a positive integer not larger than 100. The input is terminated by end-of-file (EOF). The size of input file does not exceed 1 MB.

Output data

For each test case, output one of the following:

Examples

Input example #1
6
1 1
1 2
1 3
2 1
2 2
2 3
6
1 1
1 2
1 3
2 3
2 2
2 1
2
1 1
2 2
4
1 2
1 1
2 1
2 2
7
1 2
1 5
1 1
1 3
2 5
1 4
2 4
Output example #1
queue
not sure
impossible
stack
priority queue