# coding=utf-8
from datetime import datetime
import sys

v, w = map(int, input().split())
a = []


def getDif(a, b):
    # 通过datetime模块计算时间差
    # 例如 传入 08:03 和 08:08 ，返回5
    a = datetime.strptime(a, "%H:%M")
    b = datetime.strptime(b, "%H:%M")
    return (b - a).seconds // 60


def getCnt(first, last):
    p = first
    k = 1
    s1 = a[first][2:]
    for i in range(first + 1, last):
        s2 = a[i][2:]
        if __________:
            k += 1
            p = i
            __________
    return k


for line in sys.stdin:
    a.append(line.strip())  # 删除结尾的换行符
a.append(" ")

ans = 0
n = len(a)
j = 0
for i in range(1, n):
    if a[j][0] != a[i][0]:
        __________
        j = i
print(ans)