N = int(input())
S = list(input())
ans = 0
for i in range(1, 6):
    if S[-i] != "HAPPY"[-i]:
        S[-i] = "HAPPY"[-i]
        ans += 1
for i in range(N - 5):
    if S[i : i + 5] == list("HAPPY"):
        S[i + 4] = "Z"
        ans += 1
print(ans)