Given the weight of E is empty piggy banks and weight F piggy bank with coins. In the piggy bank may be the coin of N, for each known value of Pi and the weight Wi of a coin. Find the minimum and maximum amount of money that may be in the kitty.
In the first row are the number of E and F, the second - the number N, the following N lines - two numbers, Pi and Wi. 1 ≤ E ≤ F ≤ 10000, 1 ≤ N ≤ 500, 1 ≤ Pi ≤ 50000, 1 ≤ Wi ≤ 10 000, all numbers are integers.
Two numbers are derived through the gap - minimum and maximum amounts. If the piggy bank may not have exactly the specified weight, provided that it is filled with coins given species - print "This is impossible.".
Input example #1
1000 1100 2 1 1 5 2
Output example #1