POJ 1028

#include <iostream>
#include <vector>
using namespace std;
int main(){
	vector<string> urls;
	urls.push_back("http://www.acm.org/");
	int idx = 0;
	string cmd;
	while (true) {
		cin >> cmd;
		if (cmd == "QUIT") return 0;
		else if (cmd == "VISIT") {
			for (int i=urls.size()-1; i>idx; i--) {
				urls.pop_back();
			}
			string url;
			cin >> url;
			urls.push_back(url);
			idx++;
		}
		else if (cmd == "BACK"){
			if (idx <= 0) {
				cout << "Ignored" << endl;
				continue;
			}
			idx--;
		}
		else if (cmd == "FORWARD") {
			if (idx >= urls.size()-1) {
				cout << "Ignored" << endl;
				continue;
			}
			idx++;
		}
		cout << urls[idx] << endl;
	}
	return 0;
}