#!/bin/python3
import math
import os
import random
import re
import sys
n = int(input())
s = input()
c=0
for i in range(0,n-3):
if(s[i]=='D' and s[i+1]=='U' and s[i+2]=='D' and s[i+3]=='U'):
c=c+1
print(c)
# your code goes here
IyEvYmluL3B5dGhvbjMKCmltcG9ydCBtYXRoCmltcG9ydCBvcwppbXBvcnQgcmFuZG9tCmltcG9ydCByZQppbXBvcnQgc3lzCm4gPSBpbnQoaW5wdXQoKSkKcyA9IGlucHV0KCkKYz0wCmZvciBpIGluIHJhbmdlKDAsbi0zKToKICAgIGlmKHNbaV09PSdEJyBhbmQgc1tpKzFdPT0nVScgYW5kIHNbaSsyXT09J0QnIGFuZCBzW2krM109PSdVJyk6CiAgICAgICAgYz1jKzEKcHJpbnQoYykKICAgIAojIHlvdXIgY29kZSBnb2VzIGhlcmU=