Problem:
Score : 500 points

Problem Statement

A robot is put at the origin in a two-dimensional plane.
Initially, the robot is facing in the positive x-axis direction.

This robot will be given an instruction sequence s.
s consists of the following two kinds of letters, and will be executed in order from front to back.

F : Move in the current direction by distance 1.

T : Turn 90 degrees, either clockwise or counterclockwise.

The objective of the robot is to be at coordinates (x, y) after all the instructions are executed.
Determine whether this objective is achievable.

Constraints

s consists of F and T.

1 \leq |s| \leq 8 000

x and y are integers.

|x|, |y| \leq |s|

Input

Input is given from Standard Input in the following format:

s
x y

Output

If the objective is achievable, print Yes; if it is not, print No.

Sample Input 1

FTFFTFFF
4 2

Sample Output 1

Yes

The objective can be achieved by, for example, turning counterclockwise in the first T and turning clockwise in the second T.

Sample Input 2

FTFFTFFF
-2 -2

Sample Output 2

Yes

The objective can be achieved by, for example, turning clockwise in the first T and turning clockwise in the second T.

Sample Input 3

FF
1 0

Sample Output 3

No

Sample Input 4

TF
1 0

Sample Output 4

No

Sample Input 5

FFTTFF
0 0

Sample Output 5

Yes

The objective can be achieved by, for example, turning counterclockwise in the first T and turning counterclockwise in the second T.

Sample Input 6

TTTT
1 0

Sample Output 6

No

Solution in Ruby (2.3.3) (judge verdict: Time Limit Exceeded)

class Problem
  def initialize(orders, x, y)
    @orders = orders.split('T')
    @x, @y = x, y
    @dp = {}
  end
  def rec_x(index, x)
    if index >= @orders.length
      @x == x
    else
      if @dp.include?("x.#{index}.#{x}")
        @dp["x.#{index}.#{x}"]
      else
        len = @orders[index].length
        @dp["x.#{index}.#{x}"] = index == 0 ? rec_x(index + 2, x + len) : rec_x(index + 2, x + len) || rec_x(index + 2, x - len)
      end
    end
  end
  def rec_y(index, y)
    if index >= @orders.length
      @y == y
    else
      if @dp.include?("y.#{index}.#{y}")
        @dp["y.#{index}.#{y}"]
      else
        len = @orders[index].length
        @dp["y.#{index}.#{y}"] = rec_y(index + 2, y + len) || rec_y(index + 2, y - len)
      end
    end
  end
  def solve
    rec_x(0, 0) && rec_y(1, 0)
  end
end

def main
  orders = STDIN.gets.chomp
  (x, y) = STDIN.gets.split(' ').map{|n| n.to_i }
  puts Problem.new(orders, x, y).solve ? 'Yes' : 'No'
end

main