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

#define rep(i,n) for (ll i=0; i<(n); ++i)
#define nall(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define Yes cout << "Yes" << "\n"
#define No cout << "No" << "\n"

template<typename T,typename U>inline bool chmax(T&a,U b){if(a<b){a=b;return 1;}return 0;}
template<typename T,typename U>inline bool chmin(T&a,U b){if(a>b){a=b;return 1;}return 0;}

using ll = long long;
using ull = unsigned long long;
using P = pair<ll,ll>;

const ll inf = (2e9)+2026;
const ll INF = (1e18)+2026;
const ll dx[] = {0,1,0,-1,1,1,-1,-1};
const ll dy[] = {1,0,-1,0,1,-1,1,-1};

//#include <atcoder/all>
//using namespace atcoder;

//using mint = atcoder::modint998244353;

using T = tuple<ll,ll,ll>;

ll testcase(){
    ll n; cin >> n;
    string s; cin >> s;
    string t = "HAPPY";
    ll ans = 0;
    for(ll i=n-5,j=0; i<n; i++, j++){
        ans += s[i]!=t[j];
        s[i] = t[j];
    }
    for(ll i=0; i+5<n; i++){
        string sub = s.substr(i,5);
        if(sub == t){
            s[i] = 'B';
            ans ++;
        }
    }
    cout << ans << endl;
    return 0;
}

int main(){
    ios::sync_with_stdio(false); 
    cin.tie(nullptr);
    //cout << fixed << setprecision(15);
    int t=1;

    #ifdef LOCAL
        t=1;
    #else
        t=1;
    #endif
    //cin >> t;

    while(t--)
    testcase();

    return 0;
}