import sys
from collections import Counter
input = sys.stdin.readline
def read_values(): return tuple(map(int, input().split()))
def read_list(): return list(read_values())

def main():
    n=int(input())
    a=read_list()
    ans = list()
    c = set()
    rc = set()
    for r in range(n):
        if a[r] in c:
            break
        c.add(a[r])
    for l in range(n - 1, -1, -1):
        if a[l] in rc:
            break
        rc.add(a[l])
    print(max(0,r-l))
    print(*range(l+1,max(l,r)+1))
        
if __name__ == "__main__":
    main()