Wave pattern all matter i have given below sir g

when input is
3 4
11 12 13 14
21 22 23 24
31 32 33 34

It gives output
11,21,31,32,22,12,13,23,33,34,31,21,END

which is wrong.
sir
give me correction on my code and then ide link plz.

code is here

#include
using namespace std;
int main()
{int n ,m;
cin>>m>>n;
int arr[n][m];
if((m>=1 && m<=10)&&((n>=1 && n<=10)))
{
for(int i=0;i<m;i++)
{
for(int j=0;j<n;j++)
{
cin>>arr[i][j];
}
}
for(int j=0;j<n;j=j+1)
{
if(j%2==0)
{
for(int i=0;i<m;i++)
{
cout<<arr[i][j]<<",";
}
}
else
{
for(int i=m-1;i>=0;i–)
{
cout<<arr[i][j]<<",";
}
}
}
}
cout<<β€œEND”;
}

@Manishkumar
There were some issues like where you have to use 'm; and β€˜n’ . I have fixed that.
And there was a minor issue while printing ", ". I have fixed that.