#include <bits/stdc++.h>
#define For(i, a, b) for(int (i)=(int)(a); (i)<(int)(b); ++(i))
#define rFor(i, a, b) for(int (i)=(int)(a)-1; (i)>=(int)(b); --(i))
#define rep(i, n) For((i), 0, (n))
#define rrep(i, n) rFor((i), (n), 0)
#define fi first
#define se second
using namespace std;
typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> pii;
typedef pair<lint, lint> pll;
template<class T> bool chmax(T &a, const T &b){if(a<b){a=b; return true;} return false;}
template<class T> bool chmin(T &a, const T &b){if(a>b){a=b; return true;} return false;}
template<class T> T div_floor(T a, T b){
    if(b < 0) a *= -1, b *= -1;
    return a>=0 ? a/b : (a+1)/b-1;
}
template<class T> T div_ceil(T a, T b){
    if(b < 0) a *= -1, b *= -1;
    return a>0 ? (a-1)/b+1 : a/b;
}

constexpr lint mod = 1e9+7;
constexpr lint INF = mod * mod;
constexpr int MAX = 200010;

int main(){
    int n;
    scanf("%d", &n);
    int w[n], sum = 0;
    rep(i, n) scanf("%d", &w[i]), sum += w[i];
    if(sum % 2){
        puts("impossible");
        return 0;
    }

    bool dp[n+1][10010];
    rep(i, n+1)rep(j, 10010) dp[i][j] = false;
    dp[0][0] = true;
    rep(i, n)rep(j, 10010)if(dp[i][j]){
        dp[i+1][j] = true;
        dp[i+1][j+w[i]] = true;
    }
    puts(dp[n][sum/2] ? "possible" : "impossible");
}