#include <array>
#include <cstdint>
#include <iostream>
#include <vector>
#include <string>
#include <utility>

int main() {
    int32_t r, c, s, t;
    std::cin >> r >> c >> s >> t;
    std::vector<std::string> grid(r);
    // adding a right column simplifies the stack logic
    for (auto& row : grid) {
        std::cin >> row;
        row.push_back('0');
    }
    ++c;

    std::vector<std::vector<int32_t>> rowSum(r, std::vector<int32_t>(c, 0));
    for (int32_t i = 0; i < r; ++i) {
        rowSum[i][0] = grid[i][0] == '.';
        for (int32_t j = 1; j < c; ++j) {
            rowSum[i][j] = grid[i][j] == '.' ? rowSum[i][j - 1] + 1 : 0;
        }
    }

    std::vector<std::vector<int32_t>> colSum(r, std::vector<int32_t>(c, 0));
    for (int32_t j = 0; j < c; ++j) {
        colSum[0][j] = grid[0][j] == '.';
    }
    for (int32_t i = 1; i < r; ++i) {
        for (int32_t j = 0; j < c; ++j) {
            colSum[i][j] = grid[i][j] == '.' ? 1 + colSum[i - 1][j] : 0;
        }
    }

    auto check = [s, t](int32_t curW, int32_t curH) -> bool {
        return (curW >= s && curH >= t) || (curW >= t && curH >= s);
    };
    int64_t ans = 0;
    for (int32_t i = 0; i < r; ++i) {
        std::vector<std::array<int32_t, 2>> stk;
        for (int32_t j = 0; j < c; ++j) {
            int32_t src = j;
            while (!stk.empty() && stk.back()[1] > colSum[i][j]) {
                auto [l, curH] = stk.back();
                stk.pop_back();
                int32_t curW = j - l;
                ans += check(curW, curH) && (i + 1 == r || rowSum[i + 1][j - 1] < curW);
                src = l;
            }
            if (colSum[i][j] && (stk.empty() || colSum[i][j] > stk.back()[1]))
                stk.push_back({src, colSum[i][j]});
        }
    }

    std::cout << ans << '\n';

    return 0;
}