- Time limit: 1.00 s
- Memory limit: 512 MB
Input
The first input line has an integer $n$: the size of the pyramid.
The next line has $n$ integers $a_1,a_2,\dots,a_n$: the bottom row of the pyramid.
Output
Print one integer: the topmost number.
Constraints
- $1 \le n \le 2 \cdot 10^5$
- $1 \le a_i \le 10^9$
Input:
8
2 10 5 12 9 5 1 5
Output:
9