Mohamed is a rich man. He is dealing with stock market. Every day he starts with N dollars (specif budget). Through the day he can sell or buy if he sell he will gain S dollars and if he buy he will lose B dollars. Mohamed needs your help given his initial budget and amount he will gain if he sell stock, amount he will lose if he buy stock and sequence of actions sell or buy, print his total money after the day.

Input

Input will contain 3 lines

First line : contain 3 integers N S B where 1 ≤ N, S, B ≤ 100000. N is initial budget, S is amount of sell, B amount for buy.

Second line : contain 1 integer M where M is number of actions for the day, 1 ≤ M ≤ 100

Third line : M characters, each character will be B or S such that B represent buy and S represent sell.

Output

Print the Mohamed total money after all day actions and if the amount of money is less than 0 just print 0.

Print a new line after the test case.

Example

Input:
100 10 4
4
B B S B

Output:
98