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)

$s = gets.chomp.split("")
$x,$y = gets.split(" ").map(&:to_i)

# direction => 0:上 1:右 2:下 3:左
def dfs(i, coordinate,direction)
  coordinate = coordinate.clone
  direction = Marshal.load(Marshal.dump(direction))

  direction = 4-direction.abs unless direction.between?(0,3)

  if $s[i] == "F"
    case direction
      when 0
        coordinate[1] += 1
      when 1
        coordinate[0] += 1
      when 2
        coordinate[1] -= 1
      when 3
        coordinate[0] -= 1
    end
  end

  #puts "i:#{i} op:#{$s[i]} c:#{coordinate} d:#{direction}"

  # 向きを変える→左回転か右回転か
  if $s[i] == "T"
    if (dfs(i+1,coordinate,direction-1)) == [$x,$y]
      puts "Yes"
      exit
#      return "Yes"
    end
    if dfs(i+1,coordinate,direction+1) == [$x,$y]
      puts "Yes"
      exit
#      return "Yes"
    end
    return "No"
  end


  if i >= $s.size-1
    return coordinate
  else
    if dfs(i+1,coordinate,direction) == [$x,$y]
      puts "Yes"
      exit
#      return "Yes"
    end
  end

  return "No"
end

puts dfs(0,[0,0],1)