#include <stdio.h>
#include <stdbool.h>

int main() {
    int n;
    scanf("%d\n", &n);

    int pack_size = n / 10;
    int testno = 0;
    int result = 0;
    bool correct = true;

    for (int i = 0; i < n; ++i) {
        char verdict;
        scanf("%c", &verdict);

        correct = correct && (verdict == 'T');
        ++testno;

        if (testno == pack_size) {
            testno = 0;
            result += correct;
            correct = true;
        }
    }

    printf("%d\n", result);

    return 0;
}