import std.algorithm;
import std.array;
import std.conv;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

int readint() {
    return readln.chomp.to!int;
}

int[] readints() {
    return readln.split.map!(to!int).array;
}

bool calc(int[] xs) {
    int sum = xs.sum;
    if (sum % 2 == 1)
        return false;

    int n = sum / 2;
    auto dp = new bool[](n + 1);
    dp[0] = 1;
    foreach (x; xs) {
        for (int i = n - x; i >= 0; i--) {
            dp[i + x] = dp[i + x] || dp[i];
        }
    }
    return dp[n];
}

void main() {
    readint();
    auto xs = readints();
    writeln(calc(xs) ? "possible" : "impossible");
}