Students Marks Sum

Source: HackerRank

Version: Phuoc Hung OJ Extended

Problem Statement

You are given marks $M=(m_0,m_1,\ldots,m_{n-1})$ for $n$ students.

• Even indices $0,2,4,\ldots$ are boys' marks.
• Odd indices $1,3,5,\ldots$ are girls' marks.

A character $g$ selects the required group:

• b: sum the marks at even indices;
• g: sum the marks at odd indices.

Compute the requested sum.

Input

• The first line contains an integer $n$.
• Each of the next $n$ lines contains one integer $m_i$.
• The final line contains b or g.

Output

Print one integer: the requested sum of marks.

Subtasks

Subtask 1 (100 points): $1\le n\le1000$; $1\le m_i\le1000$; $g\in\{\texttt{b},\texttt{g}\}$.

Examples

Input

5
1
2
3
4
5
g

Output

6

Explanation

For g, we add odd-indexed elements: $m_1+m_3=2+4=6$.