Snake

Write a program that prints an integer located at line x and column y of matrix n × m that is filled like a snake:

Input

Given the integers n, m, x, y (1 ≤ x ≤ n ≤ 50, 1 ≤ y ≤ m ≤ 50). Here n is number of matrix lines, m is number of matrix columns, x and y are the numbers of row and column of element to print.

Output

Print the element of line x and column y.

Examples