#include <iostream>
#include <cstdio>

int main(){
    int N;
    int W[100];

    std::cin >> N;

    int sum = 0;
    for(int i=0;i<N;i++){std::cin >> W[i]; sum += W[i];}

    if(sum % 2 == 1){puts("impossible"); return 0;}
    
    bool dp[101][5001];
    std::fill(&dp[0][0], &dp[0][0]+101*5001, false);
    dp[0][0] = true;

    for(int i=0;i<N;i++){
        for(int j=0;j<=sum/2;j++){
            if(dp[i][j]){
                dp[i+1][j] = true;
            }
            if(dp[i][j] && j + W[i] <= sum/2){
                dp[i+1][j+W[i]] = true;
            }
        }
    }

    if(dp[N][sum/2]){
        puts("possible");
    }else{
        puts("impossible");
    }
}