#include <bits/stdc++.h>
using namespace std;
#define LIFESUCKS \
ios_base::sync_with_stdio(0); \
cin.tie(0); \
cout.tie(0);
#define ll long long
#define pll pair<ll, ll>
#define mll map<ll, ll>
#define vll vector<ll>
#define pb push_back
#define fi first
#define se second
#define all(c) c.begin(), c.end()
#define debug cout << "I Love You\n";
#define Bitc(x, j) ((x >> j) & 1)
#define fu(i, a, b) for (ll i = a; i <= b; i++)
#define fd(i, b, a) for (ll i = b; i >= a; i--)
const ll Mod = 1e9 + 7;
const ll inf = (1ll << 31);
const ll lnf = (1ll << 60);
template <class X, class Y>
bool minimize(X &x, const Y &y) {
X eps = 1e-9;
if (x > y + eps) {
x = y;
return 1;
}
return 0;
}
template <class X, class Y>
bool maximize(X &x, const Y &y) {
X eps = 1e-9;
if (x + eps < y) {
x = y;
return 1;
}
return 0;
}
int64_t add(ll &a, ll b) {
a += b;
if (a >= Mod) a %= Mod;
while (a < 0) a += Mod;
return a;
}
int64_t mul(ll a, ll b) {
a = 1ll * a * b % Mod;
return a;
}
#define mxn 1'000'007
ll n, m, d, k;
void lovesper(const ll TestCase) {
cin >> n >> m >> d >> k;
vector<vll> g( n +7, vll ( m + 7, 0));
vector<vll> pref( n +7, vll ( m + 7, 0));
fu ( i, 1, n ) fu ( j, 1, m ) {
char x; cin >> x;
// cout << x << ' ' << " \n"[j == m];
if ( x == 'M' ) g[i][j] = -1;
else g[i][j] = ( x == 'S');
pref[i][j] = pref[i - 1][j] + pref[i][j - 1] - pref[i - 1][j - 1] + ( x == 'S' );
}
ll sad = 0;
fu ( i, 1, n ) fu ( j, 1, m ) {
if ( g[i][j] != -1 ) continue;
ll sum = pref[min(n, i + d)][min(m, j + d)] - pref[min(n, i + d)][max(0ll, j - d - 1)] - pref[max(0ll, i - d - 1)][min(m, j + d)] + pref[max(0ll, i - d - 1)][max(0ll, j - d - 1)];
// cerr << i << ' ' << j << " " << sum << '\n';
if ( sum >= k) sad += 1;
}
cout << sad;
}
signed main() {
LIFESUCKS
#define name "lovesper"
// freopen(name".inp", "r", stdin);
// freopen(name".out", "w", stdout);
ll test = 1;
// cin >> test;
for (int i = 1; i <= test; i++) {
lovesper(i);
if (i < test) cout << '\n';
}
return 0;
}
