import sys # sys.setrecursionlimit(200005) int1 = lambda x: int(x)-1 pDB = lambda *x: print(*x, end="\n", file=sys.stderr) p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr) def II(): return int(sys.stdin.readline()) def LI(): return list(map(int, sys.stdin.readline().split())) def LLI(rows_number): return [LI() for _ in range(rows_number)] def LI1(): return list(map(int1, sys.stdin.readline().split())) def LLI1(rows_number): return [LI1() for _ in range(rows_number)] def SI(): return sys.stdin.readline().rstrip() dij = [(0, 1), (-1, 0), (0, -1), (1, 0)] # dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)] # inf = (1 << 63)-1 inf = (1 << 31)-1 # md = 10**9+7 md = 998244353 from collections import defaultdict n = II() pp = defaultdict(list) mx = 0 X = Y = 0 for i in range(n): x, y = LI() x %= 10 y %= 7 pp[x, y].append(i+1) if len(pp[x, y]) > mx: mx = len(pp[x, y]) X, Y = x, y print(len(pp[X, Y])) print(*pp[X, Y])