#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int r, c, d, k; cin >> r >> c >> d >> k;
vector<vector<int>> a(r + 1, vector<int>(c + 1, 0)), b(r + 1, vector<int>(c + 1, 0));
for (int i = 1; i <= r; i++)
for (int j = 1; j <= c; j++) {
char c; cin >> c;
if (c == 'M') a[i][j] = 1;
if (c == 'S') b[i][j] = 1;
}
vector<vector<int>> p(r + 1, vector<int>(c + 1, 0));
for (int i = 1; i <= r; i++)
for (int j = 1; j <= c; j++)
p[i][j] = b[i][j] + p[i - 1][j] + p[i][j - 1] - p[i - 1][j - 1];
function<int(int, int, int, int)> f = [&](int i, int j, int k, int l) {
k = min(k, r), l = min(l, c), i = max(1, i), j = max(1, j);
return p[k][l] - p[k][j - 1] - p[i - 1][l] + p[i - 1][j - 1];
};
vector<vector<int>> ans(r + 1, vector<int>(c + 1, 0));
for (int i = 1; i <= r; i++)
for (int j = 1; j <= c; j++)
if (a[i][j] == 1)
if (f(i - d, j - d, i + d, j + d) >= k)
ans[i][j] = 1;
int ret = 0;
for (int i = 1; i <= r; i++)
for (int j = 1; j <= c; j++)
ret += ans[i][j];
cout << ret;
}
