8663: ITP2_1_A : Vector
[Creator : ]
Description
For a dynamic array A={$a_0,a_1,...$} of integers, perform a sequence of the following operations:
- pushBack(x): add element x at the end of A
- randomAccess(p):print element $a_p$
- popBack(): delete the last element of A
Input
The input is given in the following format.
$q$
query$_1$
$:$
query$_q$
Each query query$_i$ is given by
or
or
where the first digits 0, 1 and 2 represent pushBack, randomAccess and popBack operations respectively.
randomAccess and popBack operations will not be given for an empty array.
$q$
query$_1$
$:$
query$_q$
Each query query$_i$ is given by
0 x
or
1 p
or
2
where the first digits 0, 1 and 2 represent pushBack, randomAccess and popBack operations respectively.
randomAccess and popBack operations will not be given for an empty array.
Output
For each randomAccess, print $a_p$ in a line.
Constraints
1≤q≤200,000
0≤p< the size of A
−1,000,000,000≤x≤1,000,000,000
0≤p< the size of A
−1,000,000,000≤x≤1,000,000,000
Sample 1 Input
8
0 1
0 2
0 3
2
0 4
1 0
1 1
1 2
Sample 1 Output
1
2
4