function Main(input: string): void {
  const nums: number[] = input.split(' ').map(str => parseInt(str));

  for (let num = 1; num <= 10; num++) {
    if (!nums.includes(num)) {
      console.log(num);
      break;
    }
  }
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));