Help me in solving PPSCPP52 problem

help
,
1

My issue

include <bits/stdc++.h>
using namespace std;

int main() {
// your code goes here
int N;
cin >> N;
int courses=2N;
cout << courses;
return 0;
}
how this code is wrong

My code

#include <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here
    int N;
    cin >> N;
    int courses=2N;
    cout << courses;
    return 0;
}

Learning course: Introduction to C++
Problem Link: CodeChef Learn Problem Solving in Introduction to C++