There are N Reversi pieces arranged in a row. (A Reversi piece is a disc with a black side and a white side.) The state of each piece is represented by a string S of length N. If S_i=B, the i-th piece from the left is showing black; If S_i=W, the i-th piece from the left is showing white.

Consider performing the following operation:

• Choose $i (1 \leq i < N)$ such that the i-th piece from the left is showing black and the (i+1)-th piece from the left is showing white, then flip both of those pieces. That is, the i-th piece from the left is now showing white and the (i+1)-th piece from the left is now showing black.

Find the maximum possible number of times this operation can be performed.

Constraints

• $1 \leq |S| \leq 2\times 10^5$
• S_i=B or W

Input

Input is given from Standard Input in the following format:

S

Output

Print the maximum possible number of times the operation can be performed.

Examples

Input

BBW

Output

2

Input

BWBWBW

Output

6

见题面

见题面