730 B | 730 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from decimal import Decimal
BLANK = " "
inp = input
# inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
N, H, W = mii()
l = mii()
d = [0] * (N * W)
for i in range(N):
if i % 2 == 1:
start = W * i - l[i]
for j in range(start, start + W):
d[j] = i + 1
else:
ed = W * (i + 1) + l[i]
for j in range(ed - W, ed):
d[j] = i + 1
p(d.count(0) * H)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()