import sys
input = sys.stdin.readline

N=int(input())
S=input().strip()

ANS=0
if "BB" in S:
    ANS+=1

flag=0
for i in range(1,N):
    if S[i-1]=="A" and S[i]=="A":
        ANS+=1
        flag=0
    if S[i-1]=="A" and S[i]=="B":
        if flag==0:
            ANS+=1
        else:
            flag=0
    if S[i-1]=="B" and S[i]=="A":
        ANS+=1
        flag=1

print(ANS)