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