#include <bits/stdc++.h>

using namespace std;

int main()
{
    double tb;
    cin>>tb;
    if(tb>=9) cout<<'A';
    else if(tb>=7) cout<<'B';
    else if(tb>=5) cout<<'C';
    else cout<<'D';
}

#include <iostream>
using namespace std;

int main() {
    float diemTB;
    char loaiHS;

    cout << "Nhap diem trung binh: ";
    cin >> diemTB;

    if (diemTB >= 9) {
        loaiHS = 'A';
    } else if (diemTB >= 7) {
        loaiHS = 'B';
    } else if (diemTB >= 5) {
        loaiHS = 'C';
    } else {
        loaiHS = 'D';
    }

    cout << "Loai hoc sinh: " << loaiHS << endl;
    return 0;
}