n = int(input())
s = list(input())
boo = True
flag = True
ans = 0
for i in range(n-1):
    if s[i] == "A" and s[i+1] == "A":
        boo = True
        ans += 1
    elif s[i] == "B" and s[i+1] == "B":
        boo = False
        if flag :
            ans += 1
            flag = False
    elif s[i] == "B" and s[i+1] == "A":
        boo = False
        ans += 1
    else:
        if boo:
            ans += 1
        boo = True
    #print(ans,i)

print(ans)