B"There are n cities along the road, which can be represented as a straight line. The i -th city is situated at the distance of a_i kilometers from the origin. All cities are situated in the same direction from the origin. There are m trucks travelling from one city to another. Each truck can be described by 4 integers: starting city s_i , finishing city f_i , fuel consumption c_i and number of possible refuelings r_i . The i -th truck will spend c_i litres of fuel per one kilometer. When a truck arrives in some city, it can be refueled (but refueling is impossible in the middle of nowhere). The i -th truck can be refueled at most r_i times. Each refueling makes truck's gas-tank full. All trucks start with full gas-tank. All trucks will have gas-tanks of the same size V litres. You should find minimum possible V such that all trucks can reach their destinations without refueling more times than allowed. First line contains two integers n and m ( 2 <= n <= 400 , 1 <= m <= 250000 ) -- the number of cities and trucks. The second line contains n integers a_1, a_2, ... , a_n ( 1 <= a_i <= 10^9 , a_i < a_{i+1} ) -- positions of cities in the ascending order. Next m lines contains 4 integers each. The i -th line contains integers s_i , f_i , c_i , r_i ( 1 <= s_i < f_i <= n , 1 <= c_i <= 10^9 , 0 <= r_i <= n ) -- the description of the i -th truck. Print the only integer -- minimum possible size of gas-tanks V such that all trucks can reach their destinations. Let's look at queries in details: "...