Tontti

#!/usr/bin/env python
# -*- coding: utf-8 -*-

from sys import stdin


def readline():
    return stdin.readline().strip()

def get_vars():
    global n, m, x
    row1 = readline().split(' ')
    n = int(row1[0]) # Korkeus
    m = int(row1[1]) # Leveys
    x = int(row1[2]) # Tavoite
get_vars()

def isqrt(n):
    x = n
    y = (x + 1) // 2
    while y < x:
        x = y
        y = (x + n // x) // 2
    return x
    

def is_star(char):
    return char == '*'


def run():
    metsa = []
    for i in xrange(n):
        metsa.append(map(is_star, readline()))
    
    vaihtoehtoja = 0

    sqrt_x = isqrt(x) - 1
    
    first_w = max(1, sqrt_x)
    min_dim = min(n, m)
    
    block_w = 0
    for row in metsa[:first_w]:
        block_w += row[:first_w].count(True)
    block = block_w
    
    # Generate first bars
    bars_x = []
    for y2 in xrange(m):
        bar = 0
        for x2 in xrange(first_w):
            if metsa[x2][y2]:
                bar += 1
        bars_x.append(bar)
    bars_x_w = list(bars_x)
    
    bars_y = []
    for x2 in xrange(n):
        bar = 0
        for y2 in xrange(first_w):
            if metsa[x2][y2]:
                bar += 1
        bars_y.append(bar)
    
    for w in xrange(first_w, min_dim):
        wi = w - 1
        block_x = block
        
        for x1 in xrange(n-wi):
            for y1 in xrange(m-wi):
                if block == x:
                    vaihtoehtoja += 1
                
                if not y1 == m-wi-1:
                    block += bars_x[y1+w]
                    block -= bars_x[y1]
                    
            if not x1 == n-wi-1:
                block_x += bars_y[x1+w]
                block_x -= bars_y[x1]
                block = block_x
                
                # Recalculate x-bars
                for y2 in xrange(m):
                    diff = 0
                    if metsa[x1][y2]:
                        diff -= 1
                    if metsa[x1+w][y2]:
                        diff += 1
                    bars_x[y2] += diff
        if not w == min_dim-1:
            block_w += bars_x_w[w]
            block_w += bars_y[w]
            # Corner
            if metsa[w][w]:
                block_w += 1
            block = block_w
        
        # Calc new starting bars
        for y2 in xrange(m):
            if metsa[w][y2]:
                bars_x_w[y2] += 1
        bars_x = list(bars_x_w)
        
        for x2 in xrange(n):
            if metsa[x2][w]:
                bars_y[x2] += 1
    print(vaihtoehtoja)
run()

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 7

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 8

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 9

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 10

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 11

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 13

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 15

Group: 3

Verdict: TIME LIMIT EXCEEDED