'use strict'
function main(inp) {
  inp = inp.trim().split('\n')
  const N = Number(inp.shift())
  inp = inp[0].split(' ').map(n => Number(n));

  let ans = []
  for (let i = 0; i < N; i++) {
    if (inp[i] > 1) return console.log(-1) 
    if (inp[i] === 1) ans.push(i + 1)
  }
  if (ans.length) {
    console.log(ans.length)
    console.log(ans.join(' '))
  } else {
    console.log(0)
  }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));
