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package main

import (
	"fmt"
	"os"
	"bufio"
	"strconv"
)

const (
	datapath = "crossing.txt"
	datasize = 3141560
)

func main() {
	path := datapath

	f, err := os.Open(path)
	if err != nil {
		panic(err)
	}

	who   := make([]int, datasize, datasize)	// who is where index
	where := make([]int, datasize, datasize)	// where is who index
	scanner := bufio.NewScanner(f)

	datacnt := 1
	for scanner.Scan() {
		n, err := strconv.Atoi(scanner.Text())
		if err != nil {
			panic(err)
		}
		who[datacnt] = n
		where[who[datacnt]] = datacnt
		datacnt++
	}
	f.Close()

	fmt.Println("cnt =", datacnt)

	nCross := 0
	for i:=1; i<datacnt; i++ {
		curIdx := who[i]
		for j:=0; j<curIdx; j++ {
			if where[j] > i {
				nCross++
			}
		}
	}

	fmt.Println("cross =", nCross)
}