#include <bits/stdc++.h>
using namespace std;
inline namespace
{
} // namespace
/*
- use 2D prefix sums to find number of sprinklers covering a square
*/
void solve()
{
int r, c, d, k;
cin >> r >> c >> d >> k;
vector pref(r + 1, vector(c + 1, 0));
vector grid(r, vector<bool>(c, 0));
for (int i = 0; i < r; i++)
{
for (int j = 0; j < c; j++)
{
char s;
cin >> s;
if (s == 'S')
{
pref[max(0, i - d)][max(0, j - d)]++;
pref[max(0, i - d)][min(c, j + d + 1)]--;
pref[min(r, i + d + 1)][max(0, j - d)]--;
pref[min(r, i + d + 1)][min(c, j + d + 1)]++;
}
else if (s == 'M')
grid[i][j] = 1;
}
}
vector a(r + 2, vector(c + 2, 0));
for (int i = 0; i <= r; i++)
{
for (int j = 0; j <= c; j++)
a[i + 1][j + 1] = a[i + 1][j] + a[i][j + 1] - a[i][j] + pref[i][j];
}
int cnt = 0;
for (int i = 0; i < r; i++)
{
for (int j = 0; j < c; j++)
{
if (grid[i][j] && a[i + 1][j + 1] >= k)
cnt++;
}
}
cout << cnt << '\n';
}
int main()
{
ios_base::sync_with_stdio(false), cin.tie(NULL);
solve();
return 0;
}
