import sys, math
sys.setrecursionlimit(10**8)
sys.set_int_max_str_digits(0)
INF = 1e18
MOD = 998244353
from bisect import bisect_left, bisect_right
from collections import deque, defaultdict, Counter
from itertools import product, combinations, permutations, groupby, accumulate
from heapq import heapify, heappop, heappush
from sortedcontainers import SortedList
input = sys.stdin.readline
def I():   return input().rstrip()
def II():  return int(input().rstrip())
def IS():  return input().rstrip().split()
def MII(): return map(int, input().rstrip().split())
def LI():  return list(input().rstrip())
def TII(): return tuple(map(int, input().rstrip().split()))
def LII(): return list(map(int, input().rstrip().split()))
def LSI(): return list(map(str, input().rstrip().split()))
def GMI(): return list(map(lambda x: int(x) - 1, input().rstrip().split()))
def kiriage(a, b): return (a+b-1)//b

N = II()
S = I()

change_pattern = set()

for i in range(N - 1):
    pos, nex = S[i], S[i + 1]
    if pos == nex == 'B':
        x = 10**10
    elif pos == nex == 'A':
        x = (i + 1) * N + (i + 2)
    elif pos == 'A':
        x = i + 1 
    else:
        x = i + 2
    change_pattern.add(x)

ans = len(change_pattern)
print(ans)