grading (if /else)

#include<iostream>

using namespace std;

int main()
{
    double marks;
    cin>>marks;

    //approach-1
    if(marks>=80) {
        cout<<"A\n";
    }
    if(marks>=60 && marks<80) {
        cout<<"B\n";
    }
    if(marks>=40 && marks<60) {
        cout<<"C\n";
    }
    if(marks<40) {
        cout<<"F\n";
    }

    //approach-2
    if(marks>=80) {
        cout<<"A\n";
    }
    else if(marks>=60) {
        cout<<"B\n";
    }
    else if(marks>=40) {
        cout<<"C\n";
    }
    else {
        cout<<"F\n";
    }
}