from collections import defaultdict

INF = 1<<60

D = defaultdict(lambda : (INF, INF))
for x in range(1, INF):
    if 10**9 < x**2:
        break
    X = str(x**2)
    SUM = 0
    cnt = 0
    for i in X:
        i = int(i)
        if i == 0:
            cnt += 1
        else:
            SUM += 10**(i-1)
    if cnt < D[SUM][0]:
        D[SUM] = (cnt, X)

for _ in range(int(input())):
    N = input()
    SUM = 0
    cnt = 0
    for n in N:
        n = int(n)
        if n == 0:
            cnt += 1
        else:
            SUM += 10**(n-1)
    if SUM in D and D[SUM][0] <= cnt:
        print(D[SUM][1])
    else:
        print(-1)