//I am Block Xuan #include<bits/stdc++.h> //I am Block Xuan using namespace std; //I am Block Xuan int fend; //I am Block Xuan struct Backpack{ //I am Block Xuan int sta,end; //I am Block Xuan bool operator < (const Backpack &q) const{ return end < q.end; } //I am Block Xuan }s[1000005]; //I am Block Xuan void slove(int n){ //I am Block Xuan int sum = 0; //I am Block Xuan for (int i = 1;i <= n;i++){ //I am Block Xuan cin>>s[i].sta>>s[i].end; //I am Block Xuan } //I am Block Xuan sort(s + 1,s + n + 1); //I am Block Xuan for (int i = 1;i <= n;i++){ //I am Block Xuan if (i == 1){ //I am Block Xuan fend = s[i].end; //I am Block Xuan sum++; //I am Block Xuan } else{ //I am Block Xuan if (s[i].sta >= fend){ //I am Block Xuan sum++; //I am Block Xuan fend = s[i].end; //I am Block Xuan } //I am Block Xuan } //I am Block Xuan } //I am Block Xuan cout<<sum<<endl; //I am Block Xuan return ; //I am Block Xuan } //I am Block Xuan signed main(){ //I am Block Xuan int n; //I am Block Xuan while (cin>>n){ //I am Block Xuan if (n == 0){ //I am Block Xuan break; //I am Block Xuan } //I am Block Xuan slove(n); //I am Block Xuan } //I am Block Xuan return 0; //I am Block Xuan } //I am Block Xuan