B'Little Misha goes to the programming club and solves nothing there. It may seem strange, but when you find out that Misha is filming a Minecraft series, everything will fall into place... Misha is inspired by Manhattan, so he built a city in Minecraft that can be imagined as a table of size n x m . k students live in a city, the i -th student lives in the house, located at the intersection of the x_i -th row and the y_i -th column. Also, each student has a degree of his aggressiveness w_i . Since the city turned out to be very large, Misha decided to territorially limit the actions of his series to some square s , which sides are parallel to the coordinate axes. The length of the side of the square should be an integer from 1 to min(n, m) cells. According to the plot, the main hero will come to the city and accidentally fall into the square s . Possessing a unique degree of aggressiveness 0 , he will be able to show his leadership qualities and assemble a team of calm, moderate and aggressive students. In order for the assembled team to be versatile and close-knit, degrees of aggressiveness of all students of the team must be pairwise distinct and must form a single segment of consecutive integers. Formally, if there exist students with degrees of aggressiveness l, l+1, ldots, -1, 1, ldots, r-1, r inside the square s , where l <= 0 <= r , the main hero will be able to form a team of r-l+1 people (of course, he is included in this team). Notice, that it is not required to take all students from square s to the team. Misha thinks that the team should consist of at least t people. That is why he is interested, how many squares are there in the table in which the main hero will be able to form a team of at least t people. Help him to calculate this. The first line contains four integers n , m , k and t ( 1 <= n, m <= 40 ,000 ,'...