We have a collection of 'N' stones, each stone has a positive integer weight.
On each turn, we choose the two heaviest stones and smash them together. Suppose the stones have weights 'x' and 'y' with 'x' <= 'y'. The result of this smash will be:
1. If 'x' == 'y', both stones are totally destroyed;
2. If 'x' != 'y', the stone of weight 'x' is totally destroyed, and the stone of weight 'y' has a new weight equal to 'y - x'.
In the end, there is at most 1 stone left. Return the weight of this stone or 0 if there are no stones left.
The first line of input contains the integer 'N', representing the total number of stones.
The second line of input contains 'N' single space-separated integers, representing the weights of the stones.
The only output line prints the weight of the last stone, if it exists, 0 otherwise.
You do not need to print anything; it has already been taken care of. Just implement the given functions.
1 <= N <= 10^5
1 <= W <= 10^6
Time Limit: 1 sec