#include <bits/stdc++.h>
using namespace std;
const int block=320;
int n,res,a[block];
deque<int>q[block];
signed main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);cin>>n;
	for(int i=0;i<block;++i)for(int j=0;j<block;++j)q[i].push_back(0);
	for(int i=0;i<n;++i){
		int l,r;
		cin>>l>>r;
		int li=l/block,ri=r/block,b=1;
		for(int j=r%block;j<block;++j)if(q[ri][j]){
			q[ri][j]=b=0;
			--a[ri];
			break;
		}
		if(b&&ri!=block-1){
			int I=ri+1;
			while(I<block&&!a[I])++I;
			if(I<block){
				for(int j=0;j<block;++j)if(q[I][j]){
					q[I][j]=b=0;
					--a[I];
					break;
				}
			}
		}
		res+=b;
		q[ri].erase(q[ri].begin()+r%block);
		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%block,1);
		a[li]++;
	}
	cout<<res<<endl;
}