Help me in solving MATADD problem

help
,
1

My issue

the code is showing correct output on other compilers but not on this one .Don’t know why

My code

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

int main() 
{
	// your code goes here
      int n , m;
      cin>>n>>m;
      int a[n][m];
      int b[n][m];
      for(int i = 0;i<n;i++)
      {
          for(int j = 0;j<m;j++)
          {
              cin>>a[i][j];
          }
      }
      for(int i = 0;i<n;i++)
      {
         for( int j = 0;j<m;j++)
         {
             cin>>b[i][j];
         } 
      }
      int x[n][m];
      for(int i =0;i<n;i++)
      {
        for(int j = 0;j<n;j++)
        {
            x[i][j] = a[i][j]+b[i][j];
        }  
      }
      for(int i = 0;i<n;i++)
      {
       for(int j = 0;j<m;j++)
       {
        cout<<x[i][j]<<" ";   
       }   
      }
      return  0 ;
}

Learning course: Data structures & Algorithms lab
Problem Link: https://www.codechef.com/learn/course/muj-dsa-c/MUJDSAC09/problems/MATADD