Gas Station

You have a circular route of gas stations. gas[i] is fuel at station i, cost[i] is fuel needed to reach i+1. Return the starting index that allows a full loop, or -1 if impossible.

Examples
Input: [[1,2,3,4,5],[3,4,5,1,2]]
Output: 3
Hints

Gas Station

You have a circular route of gas stations. gas[i] is fuel at station i, cost[i] is fuel needed to reach i+1. Return the starting index that allows a full loop, or -1 if impossible.