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("")
s << "T"
x, y = gets.split.map(&:to_i)
t_count = 0
f_count = 0
x_moves = []
y_moves = []
s.each do |c|
  if c == "F"
    f_count += 1
  else
    t_count += 1
    if t_count == 1
      x -= f_count
    elsif t_count.even?
      y_moves << f_count if f_count > 0
    else
      x_moves << f_count if f_count > 0
    end
    f_count = 0
  end
end
x_moves.sort!
y_moves.sort!

x_must_deduced, x_mod = ((x_moves.inject(:+) || 0) - x.abs).divmod(2)
y_must_deduced, y_mod = ((y_moves.inject(:+) || 0) - y.abs).divmod(2)

if x_mod > 0 || y_mod > 0
  puts "No"
  exit
end

if x_must_deduced > 0
  options = [0]
  until x_moves.empty?
    next_x = x_moves.shift
    break if next_x > x_must_deduced
    options += options.map{ |n| n + next_x }
    if options.include?(x_must_deduced)
      x_must_deduced = 0
      break
    end
  end
end

if y_must_deduced > 0
  options = [0]
  until y_moves.empty?
    next_y = y_moves.shift
    break if next_y > y_must_deduced
    options += options.map{ |n| n + next_y }
    if options.include?(y_must_deduced)
      y_must_deduced = 0
      break
    end
  end
end

if x_must_deduced == 0 && y_must_deduced == 0
  puts "Yes"
else
  puts "No"
end