int search(vector<int>& nums, int target) {
        int low = 0;
        int n = nums.size();
        int high = n-1;
        
        while(high>=low){
            int mid = (high+low)/2;
        if(nums[mid]==target)return mid;
        else if(target>nums[mid])
        {
            low = mid+1;
        }
        else
        {
            high=mid-1;
        }
        }
        return -1;
    }