Gas Station

There are n gas stations along a circular route. gas[i] is the gas available at station i. cost[i] is the gas needed to travel from station i to station i+1.

Starting with an empty tank at one station, return the starting station index from which you can complete the circuit, or -1 if impossible. The solution is guaranteed to be unique.

Example 1:

Input:  gas  = [1,2,3,4,5]
        cost = [3,4,5,1,2]
Output: 3

Example 2:

Input:  gas  = [2,3,4]
        cost = [3,4,3]
Output: -1

Constraints:

• n == gas.length == cost.length
• 1 <= n <= 10⁵
• 0 <= gas[i], cost[i] <= 10⁴