let x = [1, 0, -1, 0]
let i = require('fs').readFileSync('/dev/stdin', 'utf8').split('\n')
let d = parseInt(i[0])
let a = i[1].split(' ').map((e) => parseInt(e))
for (let n = d; n >= 3; n--) {
  let b = a[n]
  for (let m = 0; m <= 3; m++) {
    a[n - m] -= b * x[m]
  }
}
let o = 0
a = a.slice(0, 3)
for (let n = a.length - 1; n >= 0 ; n--) {
  if (a[n] != 0) {
    o = n
    break
  }
}
console.log(o)
console.log(a.slice(0,o+1).join(' '))