import std;
import core.bitop;

void main()
{
    auto N = readln.strip.to!int;
    auto W = readln.split.to!(int[]);

    bool[10001][100] memo;
    bool solve(int i, int left, int right)
    {
        if (i == N)
            return left == right;

        if (memo[i][left])
            return false;

        memo[i][left] = true;

        return solve(i + 1, left + W[i], right       )
            || solve(i + 1, left,        right + W[i]);
    }
    (solve(0, 0, 0) ? "possible" : "impossible").writeln;
}