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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
	"strconv"
	"time"
)

// const abcd = "abcdefghijklmnopqrstuvwxyz"
// const ABCD = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
// var dx = [...]int{0, 1, 0, -1, 1, -1, -1, 1}
// var dy = [...]int{1, 0, -1, 0, 1, 1, -1, -1}
// var inf int = 1e13

// var mod = 1000000007
var next = newScanner()

// ---------------------------------------------------------

var s string
var x, y int

func main() {
	log.SetFlags(log.Lshortfile)
	s = next.String()
	x = next.Int()
	y = next.Int()
	// d := 0 // = x, 1 = y, 2 = -x, 3 = -y,
	ans := "No"
	var dir func(int, int, int, int)
	dir = func(nx, ny, di, step int) {
		// log.Println(nx, ny, step)
		if step == len(s) {
			// log.Println(nx, ny)
			if nx == x && ny == y {
				ans = "Yes"
			}
			return
		}
		if !dist(nx, ny, step) {
			return
		}

		if s[step] == 'T' {
			if di == 0 || di == 2 {
				dir(nx, ny, 1, step+1)
				dir(nx, ny, 3, step+1)
			}
			if di == 1 || di == 3 {
				dir(nx, ny, 0, step+1)
				dir(nx, ny, 2, step+1)
			}

		} else if s[step] == 'F' {
			switch di {
			case 0:
				dir(nx+1, ny, di, step+1)
			case 1:
				dir(nx, ny+1, di, step+1)
			case 2:
				dir(nx-1, ny, di, step+1)
			case 3:
				dir(nx, ny-1, di, step+1)
			}
		}

	}
	go dir(0, 0, 0, 0)
	time.Sleep(1900 * time.Millisecond)
	fmt.Println(ans)
}

func dist(ax, ay, step int) bool {
	remainingStep := len(s) - step
	if remainingStep < abs(x-ax)+abs(y-ay) {
		return false
	}
	return true
}

// ---------------------------------------------------------

// // Pair is...
type Pair struct {
	a, b int
}

//
// // Pairs is sorted by []Pair struct
// type Pairs []Pair
//
// func (p Pairs) Len() int {
// 	return len(p)
// }
// func (p Pairs) Swap(i, j int) {
// 	p[i], p[j] = p[j], p[i]
// }
//
// func (p Pairs) Less(i, j int) bool {
// 	if p[i].a < p[j].a {
// 		return true
// 	} else if p[i].a == p[j].a {
// 		return p[i].b < p[j].b
// 	}
// 	return false
// }

// ------int method-------------------------
func in(c, a, z int) bool {
	return c >= a && c < z
}
func btoi(b bool) int {
	if b {
		return 1
	}
	return 0
}
func itob(a int) bool {
	if a == 0 {
		return false
	}
	return true
}
func max(a ...int) int {
	r := a[0]
	for i := 0; i < len(a); i++ {
		if r < a[i] {
			r = a[i]
		}
	}
	return r
}
func min(a ...int) int {
	r := a[0]
	for i := 0; i < len(a); i++ {
		if r > a[i] {
			r = a[i]
		}
	}
	return r
}
func sum(a []int) int {
	r := 0
	for i := 0; i < len(a); i++ {
		r += a[i]
	}
	return r
}
func pro(a []int) int {
	r := 1
	for i := 0; i < len(a); i++ {
		r *= a[i]
	}
	return r
}
func fill(a []int, n int) []int {
	for i := 0; i < len(a); i++ {
		a[i] = n
	}
	return a
}
func minmax(a, b int) (int, int) {
	if a > b {
		return b, a
	}
	return a, b
}
func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

// ---------- buffered scanner -----------------------------------------
func iferr(err error) {
	if err != nil {
		panic(err)
	}
}

type scanner struct {
	r   *bufio.Reader
	buf []byte
	p   int
}

func newScanner() *scanner {
	rdr := bufio.NewReaderSize(os.Stdin, 10000)
	return &scanner{r: rdr}
}
func (s *scanner) next() string {
	s.pre()
	start := s.p
	for ; s.p < len(s.buf); s.p++ {
		if s.buf[s.p] == ' ' {
			break
		}
	}
	result := string(s.buf[start:s.p])
	s.p++
	return result
}
func (s *scanner) Line() string {
	s.pre()
	start := s.p
	s.p = len(s.buf)
	return string(s.buf[start:])
}
func (s *scanner) String() string {
	return s.next()
}
func (s *scanner) Int() int {
	v, e := strconv.Atoi(s.next())
	iferr(e)
	return v
}
func (s *scanner) Ints(n int) []int {
	r := make([]int, n)
	for i := 0; i < n; i++ {
		r[i] = s.Int()
	}
	return r
}
func (s *scanner) Int64() int64 {
	v, e := strconv.ParseInt(s.next(), 10, 64)
	iferr(e)
	return v
}
func (s *scanner) Uint64() uint64 {
	v, e := strconv.ParseUint(s.next(), 10, 64)
	iferr(e)
	return v
}
func (s *scanner) Float64() float64 {
	v, e := strconv.ParseFloat(s.next(), 64)
	iferr(e)
	return v
}
func (s *scanner) pre() {
	if s.p >= len(s.buf) {
		s.readLine()
		s.p = 0
	}
}
func (s *scanner) readLine() {
	s.buf = make([]byte, 0)
	for {
		l, p, e := s.r.ReadLine()
		iferr(e)
		s.buf = append(s.buf, l...)
		if !p {
			break
		}
	}
}