#include<bits/stdc++.h>
using namespace std;
int main() {
    int n,ans=0,cur=0;;
    string s;
    cin>>n>>s;
    char last=0;
    for(char c:s){
        if(c=='a'||c=='h'){
            if(c!=last&&(last=='a'||last=='h'))cur++;
            else cur=1;
            ans=max(ans,cur);
        } 
        last=c;
    }
    cout<<ans<<'\n';
}