import turtle

qipan=[(-50,150),(50,150),(-150,50),(-150,-50)]

t1=turtle.Turtle()
t1.hideturtle()
for i in qipan:
    t1.penup()
    t1.goto(i[0], i[1])
    t1.pendown()
    if qipan.index(i)<=1:
        t1.setheading(-90)
        t1.forward(300)
    else:
        t1.setheading(0)
        t1.forward(300)

text1="O"
text2="X"
num = 0

def click(x,y):
    global num
    t1.penup()
    t1.goto(x-20,y-40)
    t1.pendown()
    if num%2==0:
        t1.write(text1, font=("Arial", 50, "normal"))
    else:
        t1.write(text2, font=("Arial", 50, "normal"))
    num+=1

turtle.listen()
turtle.onscreenclick(click)
turtle.done()