codice:
def distanza(x1, y1, x2, y2):
    dx = x2 - x1
    dy = y2 - y1
    print "dx vale" + dx
    print "dy vale" + dy
x1 = int(raw_input ("x1  vale?"))
print x1
x2 = int(raw_input ("x2  vale?"))
print x2
y1 = int(raw_input ("y1  vale?"))
print y1
y2 = int(raw_input ("y2  vale?"))
print y2
distanza(x1, y1, x2, y2)