n,m = map(int,input().split())
hotel = [[0,0,0]for i in range(n)]
yoyaku = []

for i in range(m):
    y = input().split()
    yoyaku.append(list(map(int,[y[2]]+y[3].split(":")+[y[0]]+y[1].split(":"))))
    
yoyaku.sort()
cnt=0
for i in range(m):
    for j in range(n):
        if yoyaku[i][3:]>hotel[j]:
            hotel[j]=yoyaku[j][:3]
            cnt+=1
            break
print(cnt)