City Reservoirs Connectivity

You have a number of reservoirs in a city connected by pipelines. The connectivity is described through a list of pairs of connected reservoirs. Given two reservoirs, determine if they can receive water from each other indirectly through existing connections. Start with an integer N (the number of reservoirs) and an integer M (the number of connections) followed by M pairs of reservoirs. Finally, two reservoirs will be specified. Your program should print 'YES' if the two reservoirs are connected, otherwise print 'NO'. Example Input: 5 3 1 2 2 3 4 5 1 4 Output: NO