import * as fs from 'fs';

function main(input: Array<string>) {
    const n = Number(input[0]);
    const block_length_list = input[1].split(' ').map(x => Number(x));
    
    let sorted_count = 0;
    let searching_num = n;
    for (let i = n - 1;0 <= i;i--) {
      if (block_length_list[i] === searching_num) {
        sorted_count++;
        searching_num--;
      }
    }
   
    console.log(n - sorted_count);
}

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