package main

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

func out(x ...interface{}) {
	fmt.Println(x...)
}

var sc = bufio.NewScanner(os.Stdin)

func getInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func getInts(N int) []int {
	ret := make([]int, N)
	for i := 0; i < N; i++ {
		ret[i] = getInt()
	}
	return ret
}

func getString() string {
	sc.Scan()
	return sc.Text()
}

// min, max, asub, absなど基本関数
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func asub(a, b int) int {
	if a > b {
		return a - b
	}
	return b - a
}

func abs(a int) int {
	if a >= 0 {
		return a
	}
	return -a
}

func lowerBound(a []int, x int) int {
	idx := sort.Search(len(a), func(i int) bool {
		return a[i] >= x
	})
	return idx
}

func upperBound(a []int, x int) int {
	idx := sort.Search(len(a), func(i int) bool {
		return a[i] > x
	})
	return idx
}

func main() {
	sc.Split(bufio.ScanWords)
	N := getInt()
	w := make([]int, N)
	sum := 0
	for i := 0; i < N; i++ {
		w[i] = getInt()
		sum += w[i]
	}
	if sum%2 == 1 {
		out("impossible")
		return
	}
	dp := make([][]int, N+1)
	for i := 0; i < N+1; i++ {
		dp[i] = make([]int, sum+1)
	}

	dp[0][0] = 1
	for i := 0; i < N; i++ {
		for j := 0; j <= sum; j++ {
			dp[i+1][j] |= dp[i][j]
			if j+w[i] <= sum {
				dp[i+1][j+w[i]] |= dp[i][j]
			}
		}
	}
	// out(sum / 2)
	// for i := 0; i <= N; i++ {
	// 	out(dp[i])
	// }
	if dp[N][sum/2] == 1 {
		out("possible")
	} else {
		out("impossible")
	}

}