import sys
from operator import itemgetter
input = sys.stdin.readline  # "\n"を含む

def solve(N, M, sect):
    sect.sort(key = itemgetter(1))
    temp = 0
    z = 0
    for s in sect:
        if temp < s[0]:
            temp = s[1]
            z += 1

    return N - z

def main():
    N, M = map(int, input().split())
    sect = [tuple(map(int, input().split())) for _ in range(M)]
    res = solve(N, M, sect)
    print(res)

if __name__ == "__main__":
    main()