using System;
using System.Collections.Generic;
using System.IO;
class Solution {
    static void Main(String[] args) {
            
      int noOfSteps = Convert.ToInt32(Console.ReadLine());

            string theSteps = Console.ReadLine();                                    

            int seaLevel = 0;

            int numberOfValleys = 0;

            for (int i = 0; i < noOfSteps; i++)
            {
                if (theSteps[i].ToString().Equals("D"))
                {
                    if (seaLevel == 0)
                    {
                        numberOfValleys = numberOfValleys + 1;
                    }

                    seaLevel = seaLevel - 1;
                }
                else
                    seaLevel = seaLevel + 1;
            }           

            Console.WriteLine(numberOfValleys);

                          
    }
}