Python - Problema con el contador

def omple_simplista(xifra,num_files) :

    matriu_inicial=[['' for i in range(num_files)] for i in range(num_files)]

    contador=0

    for a in range(num_files):

        for b in range(num_files):

            matriu_inicial[a][b]=int(xifra+contador)

            contador=contador+1

    return matriu_inicial

num_files = int(input(" quantes files "))

xifra= int(input(" primer element "))

matriu=[]

matriu=omple_simplista(xifra,num_files)

numero_columna_inicial=num_files//2-1

numero_columna_final=num_files//2+1

for d in matriu:

    matriu[num_files//2][num_files//2]="x"

for q in range (num_files//2+1,num_files,1):

    for w in range (numero_columna_inicial,numero_columna_final+1,1):

        matriu[q][w]="x"

    numero_columna_inicial=numero_columna_inicial-1

    numero_columna_final=numero_columna_final+1

for a in matriu:

    print(a)

filas = int(input('Ingrese num de filas: '))

inicio = int(input('Ingrese num de inicio: '))

xFila = filas / 2

xCol = [xFila]

marca = 'X'

matriz = [[] for i in range(0, filas)]

for fila in range(0, filas):

    xValCol = []

    xValFila = True if xFila <= fila else False

    for col in range(0, filas):

        if xValFila and col in xCol:

            matriz[fila].append(marca)

            xValCol.append(col)

        else:

            matriz[fila].append(inicio)

            inicio += 1

    for col in xValCol:

        xCol = list(set(xCol + [col + 1, col - 1]))

for fila in matriz:

    print(fila)

[2, 3, 4, 5, 6]

[7, 8, 9, 10, 11]

[12, 13, 'X', 14, 15]

[16, 'X', 'X', 'X', 17]

['X', 'X', 'X', 'X', 'X']

xFila = filas / 2

xCol = [xFila] if filas % 2 else [xFila - 1, xFila]

[2, 3, 4, 5]

[6, 7, 8, 9]

[10, 'X', 'X', 11]

['X', 'X', 'X', 'X']