package main

import ("flag"; "fmt")

var ngoroutine = flag.Int("n", 100000, "how many")

func f(left, right chan int) { left <- 1 + <-right }

func main() {
  flag.Parse();
  leftmost := make(chan int);
  var left, right chan int = nil, leftmost;
  for i:= 0; i< *ngoroutine; i++ {
    left, right = right, make(chan int);
    go f(left, right);
  }
  right <- 0;  // bang!
  x := <-leftmost;  // wait for completion
  fmt.Println(x);   // 100000
}