#include<iostream> #include<cstdio> using namespace std; int main() { int score; cin >> score; if (score >= 90) { cout << "A"; } else if (80 <= score && score < 90) { cout << "B"; } else if (70 <= score && score < 80) { cout << "C"; } else if (60 <= score && score < 70) { cout << "D"; } else { cout << "不及格"; } return 0; }