#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


# %%
x1, y1, x2, y2, D = map(int, read().split())


# %%
def range_sum(a, b):
    def f(x):
        return x * (x + 1) // 2
    return f(b - 1) - f(a - 1)


# %%
def f_RU(x, y, D):
    if D < 0:
        return 0
    if x == -1 or y == -1:
        return 0
    if x < y:
        x, y = y, x
    if x >= D and y >= D:
        return range_sum(1, D + 2)
    if x >= D and y < D:
        return range_sum(D - y + 1, D + 2)
    if x + y > D:
        return (x + 1) * (D - x + 1) + range_sum(D - y + 1, x + 1)
    return (x + 1) * (y + 1)


def f(x, y, D):
    if x < y:
        x, y = y, x
    if x >= 0 and y >= 0:
        return f_RU(x, y, D)
    if x < 0 and y < 0:
        return f_RU(-2 - x, -2 - y, D - 2)
    if x >= 0 and y < 0:
        return -f_RU(x, -2 - y, D - 1)


# %%
x = 0
x += f(x2, y2, D)
x += f(x1 - 1, y1 - 1, D)
x -= f(x1 - 1, y2, D)
x -= f(x2, y1 - 1, D)
print(x)