#include<stdio.h>
#define REP(i,n) for(int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=a;i<(b);i++)

int N;
int ws[101];
int dp[10001] = {0};

int s = 0;

void loop(int a,int b){
    FOR(i,b,N){
        if (!dp[ws[i]+a]){
            dp[ws[i]+a] = 1;
            loop(ws[i]+a,i+1);
        }
    }
}



void solve(){
    int ans = 0;
    if (!(s%2)){
        loop(0,0);
        if (dp[s/2]){
            ans = 1;
        }
    }
    if (ans){
        printf("possible\n");
    }else{
        printf("impossible\n");
    }

}

int main(void){
    scanf("%d",&N);
    REP(i,N){
        scanf("%d",&ws[i]);
        s += ws[i];
    }

    solve();
    return 0;
}