import math x_1, y_1 = map(int, input().split()) x_2, y_2 = map(int, input().split()) dist_o = math.sqrt((x_1 - x_2) ** 2 + (y_1 - y_2) ** 2) dist_m = abs(x_1 - x_2) + abs(y_1 - y_2) f = abs(dist_o-dist_m) print(f)