Joel wants to buy N items. He came to know that for each item there is a cash back of some amount. The i th item will have cost Ci dollar and cash back of Xi dollar. Initially, Joel has M dollars. Find the minimum value of M, that Joel must have initially, so Joel can buy all the N items.
Note: Joel can buy items in any order.
The first line will contain N, the number of items Joel has to buy. Next, N lines will have two space-separated integers Ci and Xi, representing the cost of the item and cashback Joel will get respectively for ith Item.
Output a single integer M that is the minimum dollars Joel requires initially.
1 <= N,Ci,Xi <=10^5