Излишек потребителей

There are 4 consumers in the market for sweaters. Consumer 1 is willing to spend $\pounds$ 40 on a sweater, Consumer 2 is willing to spend $\pounds$ 35, Consumer 3 is willing to spend $\pounds$ 25, and Consumer 4 is willing to spend $\pounds$ 20. Each consumer only wants to buy one sweater. If the market price for sweaters is $\pounds$ 28, what is the total consumer surplus in this market?