#include<bits/stdc++.h>
#define maxn 100005
using namespace std;
int n,L[maxn],R[maxn],ans=1,dp[maxn];
signed main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>n;for(int i=1;i<=n;++i)cin>>L[i]>>R[i];
    for(int i=0;i<=n;++i)dp[i]=100001;dp[0]=0;
    for(int i=1;i<=n;++i){
        int l=0,r=i-1,mid,st=-1;
        while(l<=r){
            mid=(l+r)>>1;
            if(dp[mid]<R[i])st=mid,l=mid+1;
            else r=mid-1;
        }
        for(int j=st;j>=0;--j)
            dp[j+1]=min(dp[j+1],max(dp[j]+1,L[i]));
    }
    for(int i=1;i<=n;++i){
        if(dp[i]!=100001)ans=i;
        else break;
    }
    cout<<ans;
	return 0;
}