#!/usr/bin/env python3
B, z, p = 1000000007, [sorted(list(map(int, input().split()))[1:]) for _ in range(int(input()))], {}
for i, s in enumerate(z):
    for a, b in ([[a, b] for j, a in enumerate(s) for b in s[j + 1:]] if len(s) <= int(len(z) ** 0.5) else []):
        p[x] = exit(print(a, b, p[x] + 1, i + 1)) if (x := a + B * b) in p else i
    if len(xs := set(s)) > int((L := len(z)) ** 0.5):
        [exit(print(*o[:2], j + 1, i + 1)) for j in range(L) if i != j and len(o := [x for x in z[j] if x in xs]) >= 2]
print("impossible")