import java.io.*;
import java.util.*;
import java.util.Stack;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
	       InputReader in = new InputReader(System.in);
	       PrintWriter w = new PrintWriter(System.out);
		//		Scanner sc = new Scanner(System.in);
//		String s = sc.nextLine();
		Stack st = new Stack();
		char[] ch = in.readString().toCharArray();
		for (int i=0;i<ch.length;i++){
			if (st.isEmpty()){
				if (ch[i]=='S'){
					st.push("S");
				}
				else{
					st.push("T");
				}
			}
			else{
				if (ch[i]=='S'){
					st.push("S");
				}
				else if (ch[i]=='T'&& st.peek()=="S"){
						st.pop();
				}
				else{
					st.push('T');
				}
			}			
		}
		 w.println(st.size());
		 w.close();
	}
	  static class InputReader {
		  
	        private final InputStream stream;
	        private final byte[] buf = new byte[8192];
	        private int curChar, snumChars;
	        private SpaceCharFilter filter;
	 
	        public InputReader(InputStream stream) {
	            this.stream = stream;
	        }
	 
	        public int snext() {
	            if (snumChars == -1)
	                throw new InputMismatchException();
	            if (curChar >= snumChars) {
	                curChar = 0;
	                try {
	                    snumChars = stream.read(buf);
	                } catch (IOException e) {
	                    throw new InputMismatchException();
	                }
	                if (snumChars <= 0)
	                    return -1;
	            }
	            return buf[curChar++];
	        }
	 
	        public int nextInt() {
	            int c = snext();
	            while (isSpaceChar(c)) {
	                c = snext();
	            }
	            int sgn = 1;
	            if (c == '-') {
	                sgn = -1;
	                c = snext();
	            }
	            int res = 0;
	            do {
	                if (c < '0' || c > '9')
	                    throw new InputMismatchException();
	                res *= 10;
	                res += c - '0';
	                c = snext();
	            } while (!isSpaceChar(c));
	            return res * sgn;
	        }
	 
	        public long nextLong() {
	            int c = snext();
	            while (isSpaceChar(c)) {
	                c = snext();
	            }
	            int sgn = 1;
	            if (c == '-') {
	                sgn = -1;
	                c = snext();
	            }
	            long res = 0;
	            do {
	                if (c < '0' || c > '9')
	                    throw new InputMismatchException();
	                res *= 10;
	                res += c - '0';
	                c = snext();
	            } while (!isSpaceChar(c));
	            return res * sgn;
	        }
	 
	        public int[] nextIntArray(int n) {
	            int a[] = new int[n];
	            for (int i = 0; i < n; i++) {
	                a[i] = nextInt();
	            }
	            return a;
	        }
	 
	        public String readString() {
	            int c = snext();
	            while (isSpaceChar(c)) {
	                c = snext();
	            }
	            StringBuilder res = new StringBuilder();
	            do {
	                res.appendCodePoint(c);
	                c = snext();
	            } while (!isSpaceChar(c));
	            return res.toString();
	        }
	 
	        public String nextLine() {
	            int c = snext();
	            while (isSpaceChar(c))
	                c = snext();
	            StringBuilder res = new StringBuilder();
	            do {
	                res.appendCodePoint(c);
	                c = snext();
	            } while (!isEndOfLine(c));
	            return res.toString();
	        }
	 
	        public boolean isSpaceChar(int c) {
	            if (filter != null)
	                return filter.isSpaceChar(c);
	            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	        }
	 
	        private boolean isEndOfLine(int c) {
	            return c == '\n' || c == '\r' || c == -1;
	        }
	 
	        public interface SpaceCharFilter {
	            public boolean isSpaceChar(int ch);
	        }
	    }
}
