let i = require('fs').readFileSync('/dev/stdin', 'utf8').split('\n')[1].split(' ').map((e) => parseInt(e))
let t = i.reduce((p,c) => p + c)
if (t % 2 == 1) console.log('impossible')
else {
  let d = Array.from(new Array(t / 2 + 1)).fill(false)
  d[0] = true
  for (let n = 0; n < i.length; n++) {
    for (let m = d.length - 1; m >= i[n]; m--) {
      d[m] |= d[m - i[n]]
    }
  }
  console.log(d.pop() ? 'possible' : 'impossible')
}