#include using namespace std; #pragma GCC optimize("Ofast") #define rep(i,n) for(ll i=0;i=0;i--) #define perl(i,r,l) for(ll i=r-1;i>=l;i--) #define fi first #define se second #define pb push_back #define ins insert #define pqueue(x) priority_queue,greater> #define all(x) (x).begin(),(x).end() #define CST(x) cout<; using vvl=vector>; using pl=pair; using vpl=vector; using vvpl=vector; const ll MOD=1000000007; const ll MOD9=998244353; const int inf=1e9+10; const ll INF=4e18; const ll dy[8]={1,0,-1,0,1,1,-1,-1}; const ll dx[8]={0,1,0,-1,1,-1,1,-1}; template inline bool chmax(T &a, T b) { return ((a < b) ? (a = b, true) : (false)); } template inline bool chmin(T &a, T b) { return ((a > b) ? (a = b, true) : (false)); } int main(){ set st;st.insert(0); ll n;cin >> n; while(n--){ ll l,r;cin >> l >> r; set nst; bool flag=false; for(auto p:st){ if(l<=p&&p=r){ if(!flag)flag=true; else nst.insert(p); } else nst.insert(p); } nst.insert(l); swap(st,nst); } cout << st.size()-1 << endl; }