#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (ll i = a; i < b; i++)
using ll = long long;

int main(){
    int n;
    string s;
    cin >> n >> s;
    int ans = 0;
    string t{"HAPPY"};
    int j = n - 5;
    rep(i, 0, 5) {
        if(s[j] != t[i]) {
            ans++;
            s[j] = t[i];
        }
        j++;
    }
    for(int i = n - 6; i >= 0; i--) {
        if(s.substr(i, 5) != t) continue;
        s[i - 4]++;
        ans++;
    }
    cout << ans << endl;
}