def rowsum(matrix):
     results = []
     for row in matrix:
         results.append(sum(row))
     return results

def columnsum(matrix):
     rows = len(matrix)
     cols = len(matrix[0])
     result = []
     for c in range(cols):
         sum = 0
         for r in range(rows):
             sum += matrix[r][c]
         result.append(sum)
     return result

def diagonal(matrix):
     diagonal = []
     rows = len(matrix)
     for row in range(rows):
         diagonal.append(matrix[row][row])
     return diagonal

def show(m):
     print matrixstring(m)

def matrixstring(m):
     rows = len(m)
     cols = len(m[0])
     result = ""
     for r in range(rows):
         for c in range(cols):
             result += str(m[r][c]).rjust(4)
         result += "\n"
     return result

def generate(rows, cols):
     import random
     m = []
     for r in range(rows):
         m.append([])
         for c in range(cols):
             m[r].append(random.randrange(100))
     return m