import math
import numpy

def shot(a, b, p):
    res = (a[0] * p + b[0] * (1 - p), a[1] * p + b[1] * (1 - p))
    return res


def get_height(point, h):
    if point[0] % 2 == 0 and point[1] % 2 == 0:
        h1 = h[int(float(point[0]) // 2)][int(float(point[1]) // 2)]
        h2 = h[int(float(point[0]) // 2 - 1)][int(float(point[1]) // 2)]
        h3 = h[int(float(point[0]) // 2)][int(float(point[1]) // 2 - 1)]
        h4 = h[int(float(point[0]) // 2 - 1)][int(float(point[1]) // 2 - 1)]
        li = [h1, h2, h3, h4]
        li = sorted(li)
        return li[2]
    y = int(float(point[0]) // 2)
    x = int(float(point[1]) // 2)
    return h[x][y]


inp = [int(x) for x in input().split()]
n = inp[1] // 2
a = (inp[2], inp[3])
b = (inp[4], inp[5])
h = []
for _ in range(n):
    h.append([int(x) for x in input().split()])
d_x = abs(a[0] - b[0])
d_y = abs(a[1] - b[1])
hori = math.sqrt(d_x ** 2 + d_y ** 2)
#print(str(hori))

sum = 0.0
cur_h = get_height(a, h)
for i in numpy.linspace(0, 1, (d_y + 1) * (d_x + 1)):
    cur_p = shot(a, b, i)
    #print(cur_p)
    new_h = get_height(cur_p, h)
    sum += abs(cur_h - new_h)
    cur_h = new_h
print(str(hori + sum))