import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line = br.readLine();
        while(line.contains("ST")){
        	line = line.replace("ST", "");
        }
        System.out.println(line.length());
    }
}
