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 C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Text;
using static System.Math;
using static Extensions;
using static MathExtensions;

public static class Program
{
    public struct State : IEquatable<State>
    {
        public int X, Y, NextIndex;
        public Direction PrevDirection;

        public State(int x, int y, int nextIndex, Direction prevDirection)
        {
            X = x;
            Y = y;
            NextIndex = nextIndex;
            PrevDirection = prevDirection;
        }

        public bool Equals(State other)
            => X == other.X
            && Y == other.Y
            && NextIndex == other.NextIndex
            && PrevDirection == other.PrevDirection;

        public override bool Equals(object obj)
        {
            if (!(obj is State)) return false;
            return this.Equals((State)obj);
        }

        public override int GetHashCode()
            => X ^ Y ^ NextIndex ^ (int)PrevDirection;

        public override string ToString()
            => $"({X}, {Y}), {NextIndex}, {PrevDirection}";
    }

    public enum Direction
    {
        L, R, U, D,
    }

    public static void Solve()
    {
        var s = S; // <= 8000
        var x = I;
        var y = I;
        var cntF = s.Count(c => c == 'F'); // <= 8000
        var l1d = L1Distance(0, 0, x, y); // <= 16000
        
        if (cntF < l1d || (cntF - l1d) % 2 != 0)
        {
            Console.WriteLine("No");
            Exit(0);
        }
        
        Assert(cntF >= l1d);
        Assert((cntF - l1d) % 2 == 0);

        var rFs = new List<int>();
        {
            var flg = false;
            s.Reverse().ForEach(c =>
            {
                if (flg && c == 'F') rFs[rFs.Count - 1]++;
                else if (c == 'F') { rFs.Add(1); flg = true; }
                else if (flg && c != 'F') flg = false;
                else if (!flg && c != 'F') { rFs.Add(0); }
            });
            if (s[0] == 'T') rFs.Add(0);
        }

        var memo = new Dictionary<State, bool>();

        Func<State, bool> Inner = null; Inner = cur =>
        {
            if (memo.ContainsKey(cur)) return memo[cur];

            if (cur.NextIndex == rFs.Count)
                return memo[cur] = cur.X == 0 && cur.Y == 0 && cur.PrevDirection == Direction.L;

            var nd = rFs[cur.NextIndex];
            var ni = cur.NextIndex + 1;

            switch (cur.PrevDirection)
            {
                case Direction.L:
                case Direction.R:
                {
                    if (Inner(new State(cur.X, cur.Y - nd, ni, Direction.U))) return memo[cur] = true;
                    if (Inner(new State(cur.X, cur.Y + nd, ni, Direction.D))) return memo[cur] = true;
                    break;
                }
                case Direction.U:
                case Direction.D:
                {
                    if (Inner(new State(cur.X - nd, cur.Y, ni, Direction.L))) return memo[cur] = true;
                    if (Inner(new State(cur.X + nd, cur.Y, ni, Direction.R))) return memo[cur] = true;
                    break;
                }
            }

            return memo[cur] = false;
        };

        Repeat(4, i =>
        {
            if (!Inner(new State(x, y, 0, (Direction)i))) return;
            Console.WriteLine("Yes");
            Exit(0);
        });

        Console.WriteLine("No");
    }

    #region Scanners
    static Scanner _scanner;
    static char C => _scanner.NextChar();
    static string S => _scanner.NextString();
    static int I => _scanner.NextInt();
    static long L => _scanner.NextLong();
    static BigInteger B => _scanner.NextBigInteger();
    static double D => _scanner.NextDouble();
    static decimal M => _scanner.NextDecimal();
    #endregion

    public static void Main()
    {
        var sw = new StreamWriter(Console.OpenStandardOutput());
        sw.NewLine = "\n";
#if DEBUG
        sw.AutoFlush = true;
#else
        sw.AutoFlush = false;
#endif
        Console.SetOut(sw);
        _scanner = new Scanner(Console.OpenStandardInput());
        Solve();
        Console.Out.Flush();
    }
}

public static partial class Extensions
{
    public static int L1Distance(int x1, int y1, int x2, int y2)
        => Abs(x1 - x2) + Abs(y1 - y2);
}

#region Library
public class Scanner
{
    private readonly Stream _stream;
    private const int _bufferSize = 1024;
    private readonly byte[] _buf = new byte[_bufferSize];
    private int _len, _ptr;

    public Scanner(Stream stream)
    {
        _stream = stream;
    }

    public byte ReadByte()
    {
        if (_ptr >= _len)
        {
            _len = _stream.Read(_buf, 0, _bufferSize);
            _ptr = 0;
        }
        return _buf[_ptr++];
    }

    public char ReadChar() => (char)ReadByte();

    public string ReadLine()
    {
        var r = new StringBuilder();
        if (_ptr == 0) r.Append(ReadChar());
        for (; _ptr < _len; _ptr++) r.Append((char)_buf[_ptr]);
        return r.ToString();
    }

    public char NextChar() => char.Parse(NextString());

    public string NextString()
    {
        var r = new StringBuilder();
        var b = ReadChar();
        while (b != ' ' && b != '\n')
        {
            r.Append(b);
            b = ReadChar();
        }
        return r.ToString();
    }

    public int NextInt() => (int)NextLong();

    public long NextLong()
    {
        var r = 0L;
        var b = ReadByte();
        var n = b == '-';
        if (n) b = ReadByte();
        while (b != ' ' && b != '\n')
        {
            r = r * 10 + b - '0';
            b = ReadByte();
        }
        return n ? -r : r;
    }

    public BigInteger NextBigInteger()
    {
        var r = new BigInteger();
        var b = ReadByte();
        var n = b == '-';
        if (n) b = ReadByte();
        while (b != ' ' && b != '\n')
        {
            r = r * 10 + b - '0';
            b = ReadByte();
        }
        return n ? -r : r;
    }

    public double NextDouble()
    {
        var i = 0L;
        var b = ReadByte();
        var n = b == '-';
        if (n) b = ReadByte();
        while (b != '.' && b != ' ' && b != '\n')
        {
            i = i * 10 + b - '0';
            b = ReadByte();
        }
        if (b != '.') return n ? -i : i;
        b = ReadByte();
        var f = 0L;
        var p = 0;
        while (b != ' ' && b != '\n')
        {
            f = f * 10 + b - '0';
            b = ReadByte();
            p++;
        }
        var r = i + (double)f / MathExtensions.Pow(10, p);
        return n ? -r : r;
    }

    public decimal NextDecimal() => decimal.Parse(NextString());

    public T Next<T>(Converter<string, T> parser) => parser(NextString());
}

[DebuggerStepThrough]
public static partial class Extensions
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void Assert(bool condition)
    {
        if (!condition) throw new Exception("Assertion failed");
    }

    public static string AsString(this IEnumerable<char> source) => new string(source.ToArray());

    public static void Exit(int exitCode)
    {
        Console.Out.Flush();
        Environment.Exit(exitCode);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
    {
        foreach (var item in source) action(item);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T, _>(this IEnumerable<T> source, Func<T, _> func)
    {
        foreach (var item in source) func(item);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T>(this IEnumerable<T> source, Action<T, int> action)
    {
        var i = 0;
        foreach (var item in source) action(item, i++);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T, _>(this IEnumerable<T> source, Func<T, int, _> func)
    {
        var i = 0;
        foreach (var item in source) func(item, i++);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void Repeat(int count, Action action)
    {
        for (var i = 0; i < count; i++) action();
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void Repeat(int count, Action<int> action)
    {
        for (var i = 0; i < count; i++) action(i);
    }

    public static IEnumerable<T> Repeat<T>(Func<T> func)
    {
        for (var i = 0; ; i++) yield return func();
    }

    public static IEnumerable<T> Repeat<T>(int count, Func<T> func)
    {
        for (var i = 0; i < count; i++) yield return func();
    }

    public static IEnumerable<T> Repeat<T>(Func<int, T> func)
    {
        for (var i = 0; ; i++) yield return func(i);
    }

    public static IEnumerable<T> Repeat<T>(int count, Func<int, T> func)
    {
        for (var i = 0; i < count; i++) yield return func(i);
    }

    public static void Swap<T>(ref T x, ref T y)
    {
        var tmp = x; x = y; y = tmp;
    }
}

[DebuggerStepThrough]
public static class MathExtensions
{
    public static int Gcd(int left, int right)
    {
        int r;
        while ((r = left % right) != 0) { left = right; right = r; }
        return right;
    }

    public static long Gcd(long left, long right)
    {
        long r;
        while ((r = left % right) != 0L) { left = right; right = r; }
        return right;
    }

    public static BigInteger Gcd(BigInteger left, BigInteger right)
        => BigInteger.GreatestCommonDivisor(left, right);

    public static int HighestOneBit(int x)
    {
        x |= x >> 01;
        x |= x >> 02;
        x |= x >> 04;
        x |= x >> 08;
        x |= x >> 16;
        return x - (x >> 1);
    }

    public static long HighestOneBit(long x)
    {
        x |= x >> 01;
        x |= x >> 02;
        x |= x >> 04;
        x |= x >> 08;
        x |= x >> 16;
        x |= x >> 32;
        return x - (x >> 1);
    }

    public static int Lcm(int left, int right) => left / Gcd(left, right) * right;

    public static long Lcm(long left, long right) => left / Gcd(left, right) * right;

    public static BigInteger Lcm(BigInteger left, BigInteger right)
        => left / Gcd(left, right) * right;

    public static int Pow(int value, int exponent)
    {
        var r = 1;
        while (exponent > 0)
        {
            if ((exponent & 1) == 1) r *= value;
            value *= value;
            exponent >>= 1;
        }
        return r;
    }

    public static long Pow(long value, int exponent)
    {
        var r = 1L;
        while (exponent > 0)
        {
            if ((exponent & 1) == 1) r *= value;
            value *= value;
            exponent >>= 1;
        }
        return r;
    }

    public static long Fact(int value)
    {
        var r = 1L;
        for (var i = 2; i <= value; i++) r *= i;
        return r;
    }
}
#endregion