package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
)

func main() {
	counts := make(map[string]int)
	file := os.Args[1:]
	if len(file) == 0 {
		countLines(os.Stdin, counts)
	} else {
		for _, i := range file {
			f, err := os.Open(i)
			if err != nil {
				log.Print(err)
			}
			countLines(f, counts)
			f.Close()
		}
	}
	for lines, n := range counts {
		if n > 1 {
			fmt.Printf("%d\t%s\n", n, lines)
		}
	}
}

func countLines(f *os.File, counts map[string]int) {
	input := bufio.NewScanner(f)
	for input.Scan() {
		counts[input.Text()]++
	}
}