For sorting input list use lambda function with tuple as a parameter. 1st item of tuple is a list's element: 1) All items convert from int to str 2) Add 'first zeros' to 15 symbols 3) Sort our list by reverse order 2nd item of tuple - input list element. It need for fulfilment condition: I More

Use Gauss formula S = 1/2 * |X1 * Y2 + X2 * Y3 + ... + Xn-1 * Yn + Xn * Yn - X2 * Y1 - X3 * Y2 - ... - Xn * Yn-1 - Xn * Y1| More