Mrs Brown goes up to a window to buy a cinema ticket .One person buys a ticket and walks away.There are now three people in front lf Mrs Brown and four behind.How many people go to the window to buy tikets at least?
问题描述：
Mrs Brown goes up to a window to buy a cinema ticket .One person buys a ticket and walks away.There are now three people in front lf Mrs Brown and four behind.
How many people go to the window to buy tikets at least?
答