import sys lines = {} for i , val in enumerate(sys.stdin): num = list(map(float,val.split())) lines[f"x{i+1}"] = num[0] lines[f"y{i+1}"] = num[1] if i >=1: break x1,y1,x2,y2 = lines.values() de = ((x1-x2)**2 + (y1-y2)**2)**0.5 dm = abs(x1-x2) + abs(y1-y2) print(abs(dm -de))