import sys

x = []
y = []

n = int(input())
if n == 0:
    pass
    print(0)

for i in range(n):
    a,b = list(map(int, sys.stdin.readline().rstrip('\n').split()))
    x.append(a)
    y.append(b)

m = 0

def check(i):
    if i > len(x)-1:
        return 0
    if x[0] != x[i] or y[0] != y[i]:
        y.pop(0)
        x.pop(0)
        return 1
    return 0


for i in range(1, n):
    m += check(i)

print(m)