## Số Nguyên tố:

def ktNT(n):
    if n < 2:
        return False
    
    for i in range(2, n):
        if n % i == 0:
            return False
    
    return True

n = int(input())
arr = list(map(int, input().split()))

MAX = 0

for v in arr:
    if ktNT(v) == True and v > MAX:
        MAX = v

print(MAX)

for i in range(n):
    if arr[i] == MAX:
        print(i+1, end = ' ')