#include <bits/stdc++.h> using namespace std; #define int long long using vec_int = vector<int>; using P = pair<int,int>; using T = tuple<int,int,int>; using ll = long long; #define rep(i, n) for(int i = 0; i < (int)(n); i++) signed main(){ int N, M; cin>>N>>M; vec_int L(M), R(M); rep(i,M)cin>>L.at(i)>>R.at(i); vector<P> RL(M); rep(i,M)RL.at(i) = make_pair(R.at(i), L.at(i)); sort(RL.begin(), RL.end()); int zeros = 0; int right = 0; rep(i,M){ if(RL.at(i).second>right){ right = RL.at(i).first; zeros++; } } cout<<N-zeros<<endl; return 0; }