860 B | 860 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
# sys.setrecursionlimit(10**7)
BLANK = " "
# inp = input
inp = lambda : sys.stdin.readline().rstrip()
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 gcd(a, b): return gcd(b, a % b) if b > 0 else a
def lcm(a, b): return a * b // gcd(a, b)
def solve():
n, m, k = mii()
l = [inp() for _ in range(n)]
ret = []
for i in l:
cnt = 0
for j in i:
if j == '0':
cnt += 1
else:
if cnt > 0:
ret.append(cnt)
cnt = 0
if cnt > 0:
ret.append(cnt)
ans = 0
for i in ret:
if i >= k:
ans += i - k + 1
p(ans)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()