func main()

    var n: int
    var ww: []int
    
    var wtotal : int
    
    var existed: bool
    var ww_str: [][]char
    
    do n :: cui@input().toInt(&existed)
    do ww_str :: cui@input().split(" ")
    
    do ww :: #[n]int
    do wtotal :: 0
    
    for cnt(0, n-1)
        do ww[cnt]:: ww_str[cnt].toInt(&existed)
        do wtotal :: wtotal + ww[cnt] 
    end for
    
    var res: int
    do res:: math@knapsack(ww, ww, wtotal/2, false)
    
    if (res <> wtotal/2)
        do cui@print("impossible")
    else
        do cui@print("possible")
    end if
    
end func