package main

import (
	"fmt"
	"sort"
)

func main() {
	var n int
	fmt.Scan(&n)

	weights := make([]int, n)
	for i := range weights {
		fmt.Scan(&weights[i])
	}

	fmt.Println(canMadeEqual(weights))
}

func canMadeEqual(weights []int) string {
	sort.Ints(weights)

	for i := 1; i <= len(weights)/2; i++ {
		larger := weights[len(weights)-i:]
		smaller := weights[:len(weights)-i]

		if sum(larger) == sum(smaller) {
			return "possible"
		}
	}

	return "impossible"
}

func sum(arr []int) int {
	sum := 0
	for _, v := range arr {
		sum += v
	}
	return sum
}