def min_(N, dolls):
    dolls.sort(key=lambda x: (x[1], x[0]))
    from bisect import bisect_left
    lis_ = []
    for r, R in dolls:
        pos = bisect_left(lis_, r)
        if pos == len(lis_):
            lis_.append(r)
        else:
            lis_[pos] = r
    max_ = len(lis_)
    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))