n,k = map(int,input().split())
s = [list(map(int,input())) for i in range(n)]

# DP
dp = [0] * 5 ** k
dpg = [0] * 5 ** k

for i in range(n):
	v = 0
	for j in range(k):
		v += s[i][j] * 5 ** j
	dp[v] += 1
	dpg[v] += 1

for i in range(k):
	mask = 5 ** i
	for j in range(5 ** k -1,-1,-1):
		if (j//mask)%5 < 4:
			dp[j] += dp[j+mask]
#
#print(dp)
#print(dpg)

ans = 0
for i in range(5 ** k):
	if dpg[i] < dp[i]:
		ans += dpg[i]

print(ans)