#include <iostream>
#include<algorithm>
#include<climits>
#include <stdexcept>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    string s;
    cin >> s;
    int left = 0;
    int length = 0;
    int tmplen = 0;
    int check = 0;
    for (int right = 0; right < n;) {
        if ((s[right] == 'a' && check == 2) || (s[right] == 'a' && check == 0)) {
            tmplen++;
            right++;
            check = 1;
            length = max(length, tmplen);

        }
        else if ((s[right] == 'h' && check == 1) || (s[right] == 'h' && check == 0)) {
            tmplen++;
            right++;
            check = 2;
            length = max(length, tmplen);
        }
        else {
            if (s[right] == 'a') {
                tmplen = 1;
                left = right;
                right++;
                check = 1;
            }
            else if (s[right] == 'h') {
                tmplen = 1;
                left = right;
                right++;
                check = 2;
            }
            else {
                tmplen = 0;
                left = right;
                right++;
                check = 0;
            }
        }
    }
    cout << length << '\n';
}
// 64 位输出请用 printf("%lld")