from more_itertools import *
from bisect import *
sosu = [2]
a = [True]*(10**7+100)
for i in range(3,10**7+100,2):
    if a[i] == False:
        continue
    else:
        sosu.append(i)
        for j in range(2,10**7):
            if i * j > 10**7:
                break
            a[i*j] = False

tmp = [-1]
for i in range(1,len(sosu)):
    if sosu[i]-2 == sosu[i-1]:
        tmp.append(sosu[i]*sosu[i-1])

T = int(input())

for i in range(T):
    N = int(input())
    print(tmp[bisect_right(tmp,N)-1])