import math

a, b, c = 1, 1, -2

for a0 in range(int(input())):
    N = int(input())
    D = int(math.sqrt((b**2 - 4 * a * c * N)))
    n1, n2 = (-b-D)//(2*a), (-b+D)//(2*a)
    #print(N, n1, n2)
    if n1 > 0 and N == n1*(n1+1)//2:
        print(n1)
    elif n2> 0 and N == n2*(n2+1)//2:
        print(n2)
    else:
        print(-1)