#include <iostream> using namespace std;

int main() { int score; cout << "请输入成绩（0-100）："; cin >> score;

switch (score / 10) {
    case 10:
    case 9:
        cout << "等级：A" << endl;
        break;
    case 8:
        cout << "等级：B" << endl;
        break;
    case 7:
        cout << "等级：C" << endl;
        break;
    case 6:
        cout << "等级：D" << endl;
        break;
    default:
        cout << "等级：F" << endl;
}
return 0;

}