function main(input) {
  const n = umber(input[0]);
  const block_list = input[1].map(parseFloat);

  let sorted_count = 0;
  let search_value = n;
  for (let i = block_list.length;0 <= i;i--) {
      if (block_list[i] === search_value) {
          search_value--;
          sorted_count++;
      }
  }
  
  console.log(n - sorted_count);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8').split('\n'));