#include <stdio.h>
int main()
{
    char arr[100000] = { '0' };
    int N = 0;
    scanf("%d", &N);
    scanf("%s", arr);
    int length = 0;
    int current = 0;
    char last = '\0';
    for (int i = 0; i < N; i++)
    {
        if (arr[i] != 'a' && arr[i] != 'h')
        {
            current = 0;
            last = '\0';
        }
        else
        {
            if (arr[i] != last)
                current++;
            else
                current = 1;
            last = arr[i];
            if (current > length)
                length = current;
        }
    }
    printf("%d\n", length);
    return 0;
}