title: Accessing multidimensional matrices in python
body: <pre><code>sumc=0
  t = int(input())
  while t :
      x = input().split()
      n = int(x[0])
      k = int(x[1])
      e = int(x[2])
      m = int(x[3])
      suma = [0]*(n-1)
      Matrix = []
      for i in range(n-1):
          Matrix.append([])
          for j in range(e):
              p = int(input())
              Matrix[i].append(p)
      for i in range(n-1):
          for j in range(e):
              suma[i] = suma[i] + Matrix[i][j]
      for j in range(e):
          p = int(input())
          Matrix[n-1][j].append(p)
      suma.sort(suma,suma+(n-1))
      for j in range(e-1):
          sumc  = sumc + Matrix[n-1][j]
      for z in range(m+1):
          if(suma[k-1] &lt; sumc+z):
              break
      if (z==m+1):
          print("imposible")
      else:
          arr[n-1][e-1] = z
          print(arr[n-1][e-1])
      t-=1
  </code></pre>
  
  <p>I want to access array by keeping one parameter/row/column (here row represented by (n-1), in line 21) constant. But getting error "index out of range".
  In general, how to access arrays for such type of problems where one of the parameters is/are constant.</p>
  
  <pre><code>Traceback (most recent call last):
    File "C:/Users/User/untitled/cde_chf_entexam.py", line 21, in &lt;module&gt;
      Matrix[n-1][j].append(p)
  IndexError: list index out of range
  
  Process finished with exit code 1
  </code></pre>
  
  <p>JUST SEE THE LINE 20-21 FOR THE ERROR, WHOLE CODE IS NOT NECESSARY, IT'S POSTED IF IT MIGHT HELP</p>