# import sys

# for line in sys.stdin:
#     a = line.split()
#     print(int(a[0]) + int(a[1]))
n=int(input())
s=input()
res=0
max_len=0
last=s[0]
if last=='a' or last=='h':
    res+=1


for i in s[1:]:
    
    if i=='a':
        if last=='h':
            res+=1
        else:
            res=1
    if i=='h':
        if last=='a':
            res+=1
        else:
            res=1
    last=i
    max_len=max(max_len,res)
max_len=max(max_len,res)
print(max_len)