package main

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

func main() {
	r := bufio.NewReader(os.Stdin)
	w := bufio.NewWriter(os.Stdout)
	defer w.Flush()
	var N int
	fmt.Fscan(r, &N)
	var P []int = make([]int, N)
	var idx map[int]int = make(map[int]int)
	for i := 0; i < N; i++ {
		var x int
		fmt.Fscan(r, &x)
		P[i] = x
		idx[x] = i
	}
	cnt := 0
	for i := 0; i < N-1; i++ {
		for P[i] != i + 1 {
			j := idx[P[i]-1]
			idx[P[i]], idx[P[j]] = j, i
			P[i], P[j] = P[j], P[i]
			cnt++
		}
	}
	fmt.Fprintln(w, cnt)
}