How to use a while loop for coordinated in python

I am trying to make a random game in which whichever character reaches the end first wins. I have basically the entire code made, but I need help with the end to determine who crosses the finish line first. So how would I do that?

My code is:

from turtle import Turtle
from random import randint
t = Turtle()
t.speed(0)

t.up()
t.goto(-200,0)
t.down()
t.forward(900)
t.up()
t.goto(-200,100)
t.down()
t.forward(900)
t.up()
t.goto(-200,200)
t.down()
t.forward(1000)
t.up()
t.goto(-200,-100)
t.down()
t.forward(900)
t.up()
t.goto(-200,-200)
t.down()
t.forward(1000)
t.up()
t.goto(-200,200)
t.down()
t.right(90)
t.forward(400)
t.left(90)
t.up()
t.goto(-100, -200)
t.left(90)
t.down()
t.forward(400)
t.up()
t.goto(800,-200)
t.down()
t.forward(400)
t.up()
t.goto(700,-200)
t.down()
t.forward(400)

d = Turtle()
d.speed(5)
d.color('red')
d.shape('arrow')
d.up()
d.goto(-155,150)
d.right(360)

c = Turtle()
c.speed(5)
c.color('blue')
c.shape('turtle')
c.up()
c.goto(-155,50)
c.right(360)

b = Turtle()
b.speed(5)
b.color('yellow')
b.shape('arrow')
b.up()
b.goto(-155,-50)
b.right(360)

a = Turtle()
a.speed(5)
a.color('green')
a.shape('turtle')
a.up()
a.goto(-155,-150)
a.right(360)

for i in range(350):
    a.forward(randint(1,6))
    b.forward(randint(1,6))
    d.forward(randint(1,6))
    c.forward(randint(1,6))

Any suggestion to make the code smaller would also be appreciated. I am trying to use while loop so that I can see when to stop the game as soon as the finish line is crossed.