#include<stdio.h>

int main(void){
    int N;
    scanf("%d\n",&N);
    int weights[101]={0};
    int j;
    int i;
    for(;j<N;j++){
        scanf("%d",&(weights[j+1]));
    }
    int sum=0;
    for(j=0;j<N+1;j++)sum+=weights[j];
    if(sum%2==1){
        printf("impossible\n");
        return 0;
    }
    int dp[101][10001];
    dp[0][0] = 1;
    for(i=1;i<N+1;i++)
    for(j=0;j<10001;j++){
        if ((dp[i-1][j] == 1) || ((j >= weights[i]) && (dp[i-1][j-weights[i]] == 1))){
            dp[i][j] = 1;
        }
    }
    if(dp[N][sum/2]){
        printf("possible\n");
    }
    else{
        printf("impossible");
    }

}