import math

n, x, y, z = map(int, raw_input().split())

x -= 1
y -= 1

ans = [[0 for _ in xrange(0,n)] for __ in range(0,n)]

for i in xrange(0,n):
	for j in xrange(0,n):
		if (((i + 1) / 2) % 2) == 0:
			if(((j % 4) == 0) | ((j % 4) == 3)):
				ans[i][j] = i * n + j + 1
			else:
				ans[i][j] = (n * n)-(i * n + j + 1)
		else:
			if(((j % 4) == 1) | ((j % 4) == 2)):
				ans[i][j] = i * n + j + 1
			else:
				ans[i][j] = (n * n)-(i * n + j + 1)

dist = z - ans[x][y]

for i in xrange(0,n):
	for j in xrange(0,n):
		ans[i][j] += dist

print ans