"""
[24510: 시간복잡도를 배운 도도](https://www.acmicpc.net/problem/24510)
Tier: Bronze 2
Category: 구현
"""
def solution():
ans = 0
for _ in range(int(input())):
s = input()
ans = max(ans, s.count('for') + s.count('while'))
return ans
if __name__ == '__main__':
print(solution())