Ruudukko

a = int(input())
c = []
d = []
dT = []
r = 0

def coolFunc(bla):
	return bla[0]

a2 = 0
while a2 < a:
	d.append([0, 0])
	dT.append([0, 0])
	a3 = 0
	for n in input().split():
		c.append([int(n), a2, a3])
		a3 += 1
	a2 += 1
c.sort(key = coolFunc)

a2 = 1
for n in c:
	if a2 != n[0]:
		a2 += 1
		for i in d:
			i[0] = i[1]
		for i in dT:
			i[0] = i[1]
	d[n[1]][1] += d[n[1]][0] + dT[n[2]][0] + 1
	dT[n[2]][1] += d[n[1]][0] + dT[n[2]][0] + 1

for i in d:
	r += i[1]

print(r % (1000000007))

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 4

Group: 2, 3

Verdict: ACCEPTED

Test 5

Group: 2, 3

Verdict: ACCEPTED

Test 6

Group: 2, 3

Verdict: WRONG ANSWER

Test 7

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 8

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 9

Group: 3

Verdict: TIME LIMIT EXCEEDED