gen2.py

#!/usr/bin/env python
import sys
import random


def main():
    n = random.randint(1, 1e6)
    sys.stderr.write(f"begin with {n=}\n")
    v = [x + 1 for x in range(n)]
    random.shuffle(v)
    print(n)
    for x in v:
        print(x)


if __name__ == "__main__":
    main()