diagNum45

def diagNum45(m,x,y):
#@param m: matrice di interi
#@param x: int
#@param y: int
  w = len(m[0])-1
  h = len(m)-1
  if x<0 or x>=h or y<0 or y>=w:
    return

  else:
    iter = min(w-y,h-x)
    m[x][y] = 0
    for i in range(iter):
      x+=1
      y+=1
      m[x][y] = 0