a = [47, 18]
b = [49, 19]
c = [48, 18]
d = [44, 19]
e = [42, 17]
l1 = [a, d]
l2 = [c, d, b]
l3 = [e, a, c]

lines = [l1, l2, l3]

for line in lines:
    sumX = 0
    sumY = 0
    
    for point in line:
        print point
        sumX = sumX + point[0]
        sumY = sumY + point[1]
    
    print len(line)
    cX = float(sumX) / len(line)
    cY = float(sumY) / len(line)
    print cX, cY