Q1

#include <bits/stdc++.h>
typedef int_fast64_t lli;
typedef long double ld;
using namespace std;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    lli n, correct = 0;
    cin >> n;
    for(lli i = 0; i < n; i++)
    {
        lli a, b, c;
        char op, e;
        cin >> a >> op;
        if(op == '/')
        {
            cin >> op;
        }
        cin >> b >> e >> c;
        switch(op)
        {
            case '+':
                correct += (a+b == c);
                break;
            case '-':
                correct += (a-b == c);
                break;
            case '*':
                correct += (a*b == c);
                break;
            case '/':
                correct += (b == 0 ? 0 : a/b == c);
                break;
        }
    }

    if(100*correct >= 70*n)
    {
        cout << "A\n";
    }
    else if(100*correct >= 60*n)
    {
        cout << "B\n";
    }
    else if(100*correct >= 50*n)
    {
        cout << "C\n";
    }
    else if(100*correct >= 40*n)
    {
        cout << "D\n";
    }
    else if(100*correct >= 30*n)
    {
        cout << "E\n";
    }
    else
    {
        cout << "F\n";
    }
    return 0;
}