#!/usr/bin/env python3
BASE = 1000000007
n = int(input())
L = int(n**0.5)
sets = [list(map(int, input().split()))[1:] for _ in range(n)]
pairs = {}
for i in range(n):
    if len(sets[i]) <= L:
        sets[i].sort()
        for j1 in range(len(sets[i])):
            for j2 in range(j1 + 1, len(sets[i])):
                x = sets[i][j1] + BASE * sets[i][j2]
                if x in pairs:
                    exit(print(sets[i][j1], sets[i][j2], pairs[x] + 1, i + 1))
                pairs[x] = i
    else:
        xs = set(sets[i])
        for j in range(n):
            if i != j:
                overlap = [x for x in sets[j] if x in xs]
                if len(overlap) >= 2:
                    exit(print(overlap[0], overlap[1], j + 1, i + 1))
print("impossible")