function Main(input) {
  const data = input.trim().split("\n")

  let N = parseInt(data[0])
  let weights = data[1].split(" ").map(w => parseInt(w))
  let sum = 0
  weights.forEach(w => sum += w)
  const halfOfSum = sum / 2
  if (N === 1) {
    console.log('impossible')
    return
  }
  weights.sort((a, b) => a - b)
  let set = new Set([weights[0]])
  for (let i = 1; i < N; i++) {
    let array = []
    set.forEach(w => array.push(w + weights[i]))
    array.forEach(v => { if (v <= halfOfSum) set.add(v) })
    set.add(weights[i])
  }
  const result = set.has(halfOfSum) ? 'possible' : 'impossible'
  console.log(result)
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"))