Printing a matrix in spiral order but getting an additional element

Question

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

// Printing a matrix in spiral Order

int main()
{
    int n, m;
    cin>>n>>m;

    int arr[n][m];
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
            cin>>arr[i][j];
    }

    // Spiral Order Print

    int row_start = 0, row_end = n-1, column_start = 0, column_end = m-1;

    while(row_start<=row_end && column_start<=column_end)
    {
        //For row_start
        for(int col=column_start; col<=column_end; col++)
            cout<<arr[row_start][col]<<" ";
        row_start++;
        
        cout<<endl;
        
        //For column_end
        for(int row = row_start; row<=row_end; row++)
            cout<<arr[row][column_end]<<" ";
        
        column_end--;
        
        cout<<endl;
        
        //For row_end
        for(int col = column_end; col>=column_start; col--)
            cout<<arr[row_end][col]<<" ";
        
        cout<<endl;
        
        row_end--;
        
        
        //For column_start
        for(int row=row_end; row>=row_start; row--)
            cout<<arr[row][column_start]<<" ";
        
        column_start++;

        cout<<endl<<endl<<endl;
    }


    return 0;
}

Input - 5 6

matrix -

1 5 7 9 10 11

6 10 12 13 20 21

9 25 29 30 32 41

15 55 59 63 68 70

40 70 79 81 95 105

//------------------------------------------------------------------//

Output -

1 5 7 9 10 11

21 41 70 105

95 81 79 70 40

15 9 6

10 12 13 20

32 68

63 59 55

25

29 30

29

I am printing a matrix in spiral order but am getting this last element, i.e., 29 twice. I cannot get to know why is it iterating through it again when all elements are done.