Country A and Country B were at war together. The ONLY way to get from one country to another was by crossing the bridge, which was manned by armed guards. Anybody caught trying to cross would be sent back to his own country.
It takes ten minutes to cross the bridge. Every fifteen minutes, the guards would enter a tent to eat/drink for two minutes. Mr X needs to cross the bridge. How should he do so? [Without swimming/parachuting or crossing any other way; without turning invisible and without using a Disillusionment Charm]