import random

class Matrix:
    def __init__(self, lines, cols):
        self.m = self.initialize(lines, cols)
    def initialize(self, lines, cols):
        m = {}
        m["lines"] = lines
        m["columns"] = cols
        for i in range(m["lines"]):
            for j in range(m["columns"]):
                m[i,j] = random.randrange(10)
        return m
    def show(self):
        for i in range(self.m["lines"]):
            for j in range(self.m["columns"]):
                print self.m[i,j],
            print
    def set(self, letter):
        size = self.m["lines"]
        if letter == 'Z':
            for i in range(self.m["lines"]):
                for j in range(self.m["columns"]):
                    if i == 0 or i == size-1 or i + j == size-1:
                        self.m[i,j] = "*"
                    else:
                        self.m[i,j] = " "

#  It runs like this:
# 
#  >>> m = Matrix(12, 12)
#  >>> m.show()
#  5 1 3 9 7 3 0 7 6 1 1 0
#  4 3 8 4 5 5 7 0 7 3 8 8
#  2 5 0 4 3 0 4 4 4 7 4 3
#  7 3 1 8 1 9 9 5 6 6 4 9
#  8 0 1 3 8 1 2 4 1 0 1 8
#  2 2 7 9 3 4 1 1 0 9 3 0
#  4 9 4 7 3 1 7 9 3 4 7 7
#  4 3 0 0 0 5 6 0 0 1 9 4
#  4 5 7 7 0 4 2 3 3 4 4 2
#  5 9 3 5 6 8 2 0 5 7 3 2
#  7 9 4 8 8 2 6 2 4 0 1 8
#  9 8 9 3 8 6 9 6 4 4 0 1
#  >>> m.set("Z")
#  >>> m.show()
#  * * * * * * * * * * * *
#                      *  
#                    *    
#                  *      
#                *        
#              *          
#            *            
#          *              
#        *                
#      *                  
#    *                    
#  * * * * * * * * * * * *
#  >>>