def min_(N, dolls):
    dolls.sort(key=lambda x: (x[1], x[0]))
    dp = [1] * N
    #?
    for i in range(N):
        for j in range(i):
            if dolls[j][1] <= dolls[i][0]:
                dp[i] = max(dp[i], dp[j] + 1)
    max_ = max(dp)
    return N - max_
N = int(input())
dolls = []
for _ in range(N):
    r, R = map(int, input().split())
    dolls.append((r, R))
print(min_(N, dolls))