Several choices

1#include <iostream>
2using namespace std;
3 
4int main() {
5    int marks;
6    cin >> marks;
7    if (marks >= 90) {
8        cout << "A" << endl;
9    } else if (marks >= 75) {
10        cout << "B" << endl;
11    } else if (marks >= 60) {
12        cout << "C" << endl;
13    } else {
14        cout << "F" << endl;
15    }
16    return 0;
17}