n=100
  U=runif(n)
  X=sqrt(U)
  Y=NULL
  for(i in 1:n)
   {
     V=runif(1)
     y=V*X[i]
     Y=c(Y,y)
   }
  plot(X,Y,col="blue")
  points(2/3,1/3,col="red",pch=19)

n=20000
U=runif(n)
X=U**(1/6)
Y=NULL
for(i in 1:n)
  {
    V=runif(1)
    y=V*X[i]
    Y=c(Y,y)
  }
plot(X,Y,col="blue")

points(2/3,1/3,col="red",pch=19)