from math import floor

def increaseList(lst, c,m,d):
  lst[0] += c
  lst[1] += m
  lst[2] += d
  return lst
n = int(input())

c,m,d = (0,0,0)

for i in range(n):
  cmd = [1 if x == "J" else 0 for x in input().split() ]
  c,m,d = increaseList(cmd, c,m,d)


print(floor((c+m+d)/3))