import math
N = int(input())
L = []
for i in range(N):
    a, b, c = map(int, input().split())
    L.append(a)
    L.append(b)
    L.append(c)

c = []
for i in range(10):
    c.append(0)

for i in range(3*N):
    if L[i] == 1:
        c[0] += 1
    elif L[i] == 2:
        c[1] += 1
    elif L[i] == 3:
        c[2] += 1
    elif L[i] == 4:
        c[3] += 1
    elif L[i] == 5:
        c[4] += 1
    elif L[i] == 6:
        c[5] += 1
    elif L[i] == 7:
        c[6] += 1
    elif L[i] == 8:
        c[7] += 1
    elif L[i] == 9:
        c[8] += 1
    elif L[i] == 10:
        c[9] += 1
        
cnt = 0
for i in range(10):
    while c[i] >= 2:
        c[i] -= 2
        cnt += 1
n = 0
for i in range(10):
    n += c[i]
if n > 3:
    cnt += math.floor(n / 4)

print(cnt)