#include<iostream>
#include<cassert>
using namespace std;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int N;
	string S;
	cin>>N>>S;
	int ans=0;
	for(int i=0;i<5;i++)
	{
		if(S[N-5+i]!="HAPPY"[i])ans++;
		S[N-5+i]="HAPPY"[i];
	}
	for(int j=0;j<N-5;j++)if(S.substr(j,5)=="HAPPY")ans++;
	cout<<ans<<endl;
}