#include <bits/stdc++.h> #define ll long long using namespace std; pair<int, int> tvs[105]; int main() { while (true) { int n; cin >> n; if (n == 0) return 0; for (int i = 1; i <= n; i++) { cin >> tvs[i].first >> tvs[i].second; } sort(tvs+1, tvs+n+1); long long ans = 0, curtime=0; for (int i = 1; i <= n; i++) { if (curtime > tvs[i].first) continue; int ed = tvs[i].second; if (tvs[i+1].second <= ed) { continue; } ans++; curtime = ed; } cout << ans << endl; } }