# Distance is now purely computational, needing interactive function Main to
# feed it the proper values through the parameter list.

def Distance(X1,Y1,X2,Y2):
    DeltaX = X2 - X1
    DeltaY = Y2 - Y1
    Sum = DeltaX*DeltaX + DeltaY*DeltaY
    Result = sqrt(Sum)
    return Result

def Main():
    X1 = input("Enter X1 --- ")
    Y1 = input("Enter Y1 --- ")
    X2 = input("Enter X2 --- ")
    Y2 = input("Enter Y2 --- ")
    Result  = Distance(X1,Y1,X2,Y2)
    print Result
    return