#include <bits/stdc++.h> using namespace std; const int N = 100; int n; struct st{ int l, r; bool operator<(const st& a) { return r < a.r; } } stu[N]; signed main() { while (~scanf("%d", &n) && n) { for (int i=1; i<=n; i++) { scanf("%d%d", &stu[i].l, &stu[i].r); } sort(stu+1, stu+1+n); int lst = 0, ans = 0; for (int i=1; i<=n; i++) { if (lst <= stu[i].l) { lst = stu[i].r; ans++; } } printf("%d\n", ans); } return 0; }