Problem I: Basic Data Structures - Stack

上一题 正确率: $84.51\%$ 下一题
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Time Limit $1$ 秒/Second(s) Memory Limit $512$ 兆字节/Megabyte(s)
提交总数 $807$ 正确数量 $682$
裁判形式 标准裁判/Standard Judge 我的状态 尚未尝试
难度 分类标签 STL

Description

Stack 

Stack is a container of elements that are inserted and deleted according to LIFO (Last In First Out). 

For n stack Si (i=0,1,...,n−1), perform a sequence of the following operations. 

push(t, x): Insert an integer x to St. 

top(t): Report the value which should be deleted next from St. If St is empty, do nothing. 

pop(t): Delete an element from St. If St is empty, do nothing. 

In the initial state, all stacks are empty.

Input

The input is given in the following format. nq query1 query2 : queryq Each query queryi is given by 0 t x or 1 t or 2 t where the first digits 0, 1 and 2 represent push, top and pop operations respectively. 1≤n≤1,000 1≤q≤200,000 −1,000,000,000≤x≤1,000,000,000 Sample Input 1

Output

For each top operation, print an integer in a line.

Sample Input复制

3 9
0 0 1
0 0 2
0 0 3
0 2 4
0 2 5
1 0
1 2
2 0
1 0

Sample Output复制

3
5
2