package main

import (
	"fmt"
	"time"
	"math/rand"
)

func f(n int) {
    for i := 0; i < 10; i++ {
        fmt.Println(n, ":", i)
		time.Sleep(time.Millisecond * time.Duration(rand.Intn(150)))
    }
}

func main() {
    for i := 0; i < 5; i++ {
		f(i)
	}
	fmt.Println()
	for i := 0; i < 5; i++ {
		go f(i)
	}
    var input string
    fmt.Scanln(&input)
}