#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <cstring>
#include <stack>
#include <queue>
#include <algorithm>
#include <cmath>
#include <map>
#define PI acos(-1.0)
#define ms(a) memset(a,0,sizeof(a))
#define msp memset(mp,0,sizeof(mp))
#define msv memset(vis,0,sizeof(vis))
using namespace std;
//#define LOCAL
struct Node
{
    int b;
    int e;
}t;
bool cmp(Node n1,Node n2)
{
    if(n1.e==n2.e)return n1.b<n2.b;
    return n1.e<n2.e;
}
vector<Node> v;
int main()
{
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
#endif // LOCAL
    ios::sync_with_stdio(false);
    int n;
    while(cin>>n&&n)
    {
        v.clear();
        while(n--)
        {
            cin>>t.b>>t.e;
            v.push_back(t);
        }
        sort(v.begin(),v.end(),cmp);
        int ans=1;
        for(int i=1;i<v.size();i++)
        {
            t=v[i];
            if(t.b>=v[i-1].e)ans++;
            else v.erase(v.begin()+i),i--;
        }
        printf("%d\n",ans);
    }
    return 0;
}