public int canCompleteCircuit(int[] gas, int[] cost) {
        if (gas == null || gas.length==0 || cost==null || cost.length==0){
            return 0;
        }
        else if (gas.length==1){
            return gas[0]>=cost[0]?0:-1;
        }
        Status status = new Status(0, 0);
        int carry = 0;
        for (int i=1; i<=gas.length; i++){
            carry +=gas[i-1] - cost[i-1];
            if (carry < status.gas ){
                status.index = i;
                status.gas = carry;
            }

        }
        System.out.println(status);

        return carry >=0?status.index:-1;
    }