Ball

Three cups are placed upside down in a row on a table. From left to right, the cups are numbered 1, 2, and 3. A ball is initially placed under cup 1.

For each move, two cup numbers X and Y are given. The cups with those numbers exchange their positions at the same time. The ball itself does not move while the cups are moved; after the exchange, it is covered by whichever cup is now at the ball's position.

After all M exchanges, determine the number of the cup that contains the ball.

The first line contains the number of exchanges M. M is a positive integer no greater than 50.

Each of the next M lines contains two integers X and Y, meaning that cups X and Y exchange positions. Both X and Y are at most 3, and they may be equal.

The input never produces a state where the ball is outside all cups.

Print the number of the cup containing the ball. If no cup contains the ball, print -1; however, this situation does not occur in the given input.