Compute the weighted sum of digits of a number read from the keyboard in the following sense: Let us calculate sum of digits multiplying each digit by its position (counting from the left, starting from 1). For example, given the value 1971 we calculate such weighted sum of digits (let us call it "wsd") as: wsd(1971) = 1 * 1 + 9 * 2 + 7 * 3 + 1 * 4 = 41