#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define rep(i,n) for(int i = 0; i < (int)(n); ++i) #define rrep(i,n) for(int i = 1; i <= (n); ++i) #define drep(i,n) for(int i = (n)-1; i >= 0; --i) #define srep(i,s,t) for (int i = s; i < (t); ++i) #define dsrep(i,t,s) for(int i = (t)-1; i >= (s); --i) #define rng(a) a.begin(),a.end() #define rrng(a) a.rbegin(),a.rend() #define isin(x,l,r) ((l) <= (x) && (x) < (r)) int dx4[4]={1,0,-1,0}; int dy4[4]={0,-1,0,1}; using ll = long long; using uint = unsigned; using ull = unsigned long long; using P = pair; const ll LINF = 1001002003004005006ll; const int INF = 1001001001; // const ll mod = 998244353; const ll mod = 1e9 + 7; /////////////////////////////////////////// int n, m; int main() { cin.tie(0); ios::sync_with_stdio(false); cin >> n >> m; vector

a(m); rep(i, m) { int l, r; cin >> l >> r; a[i] = {r, l}; } sort(a.begin(), a.end()); vector check; rep(i, m) { auto [r, l] = a[i]; auto it = lower_bound(check.begin(), check.end(), l); if(it == check.end()) check.push_back(r); } cout << n - check.size() << endl; }