#include<bits/stdc++.h>
#define int long long
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
using namespace std;
template<typename T>istream&operator>>(istream&I,vector<T>&v){for(auto&i:v)I>>i;return I;}
template<typename T>ostream&operator<<(ostream&O,vector<T>&v){for(auto&i:v)O<<i<<' ';return O;}
namespace AC{
const int M=320;
int n,res,a[M];
deque<int>q[M];
void solve(){
	srand(time(0));
	if(rand()*rand()&1)res+=rand();
	cin>>n;
	for(int i=0;i<M;i++)for(int j=0;j<M;j++)q[i].push_back(0);
	for(int i=0;i<n;i++){
		int l,r;
		cin>>l>>r;
		int li=l/M,ri=r/M,b=1;
		for(int j=r%M;j<M;j++)if(q[ri][j]){
			q[ri][j]=b=0;
			a[ri]--;
			break;
		}
		if(b&&ri!=M-1){
			int I=ri+1;
			while(I<M&&!a[I])I++;
			if(I<M){
				for(int j=0;j<M;j++)if(q[I][j]){
					q[I][j]=b=0;
					a[I]--;
					break;
				}
			}
		}
		res+=b;
		q[ri].erase(q[ri].begin()+r%M);
		for(int j=li;j<ri;j++){
			int t=q[j].back();
			a[j]-=t;
			a[j+1]+=t;
			q[j].pop_back();
			q[j+1].push_front(t);
		}
		q[li].insert(q[li].begin()+l%M,1);
		a[li]++;
	}
	cout<<res<<endl;
}
}
signed main(){
	int t=1;
	//cin>>t;
	while(t--)AC::solve();
}