#include <iostream>

 #include <algorithm>

 #include <cstring>

 using namespace std;

 int main()

 {

     int t, i, s, start, a[][], tt,j;

     while (cin >> t && t != )

     {

         for (i = ; i < t; i ++)

             cin >> a[i][] >> a[i][];

         for (i = ; i < t - ; i ++)            //对结束时间排序  如果相等就对开始时间从小到大排序

             for (j = i + ; j < t; j ++)

             {

                 if (a[i][] > a[j][])

                 {

                     tt = a[i][]; a[i][] = a[j][]; a[j][] = tt;

                     tt = a[i][]; a[i][] = a[j][]; a[j][] = tt;

                 }

                 if (a[i][] == a[j][])

                 {

                     if (a[i][] > a[j][])

                     {

                         tt = a[i][]; a[i][] = a[j][]; a[j][] = tt;

                         tt = a[i][]; a[i][] = a[j][]; a[j][] = tt;

                     }

                 }

             }

                 s  = ; start = ;

                 for (i = ; i < t;  i ++)

                 {

                     if (a[i][] >= a[start][])        //计算最多节目

                     {

                         //cout<<a[i][0]<<"      "<<a[i][1]<<endl;

                         start = i;

                         s++;

                     }

                 }

                cout<<s<<endl;

             }

         return ;

     }