M=10**7
D=[1]*(M)
D[0]=0
D[1]=0
C=[]
for i in range(2,M):
  if D[i]==1:
    d=i
    C.append(i)
    while d+i<M:
      d+=i
      D[d]=0
  
E=[]
for c in C:
  if D[c+2]==1:
    E.append(c*(c+2))


import bisect 
Q=int(input())
for i in range(Q):
  N=int(input())
  d=bisect.bisect_right(E,N) 
  if d==0:
    print(-1)
  else:
    print(E[d-1])