#include<bits/stdc++.h>
#define st first
#define nd second
#define pb push_back
#define ppb pop_back
#define ii pair<int,int>
#define ll long long
#define umin(x,y) x=min(x,y)
#define umax(x,y) x=max(x,y)
#define orta ((bas+son)>>1)
#define sz(x) ((int)x.size())
#define all(x) x.begin(),x.end()
#define inf 2000000000
#define N 500005
#define MOD 1000000007
using namespace std;
struct Q {
int l,r,v;
};
int n,m,d,k,ans;
vector<Q> L[N];
vector<int> M[N];
char s[N];
int S[N<<2],lazy[N<<2];
void shift(int node,int val) {
S[node]+=val;
lazy[node]+=val;
}
void push(int node) {
shift(node<<1,lazy[node]);
shift(node<<1|1,lazy[node]);
lazy[node]=0;
}
int get(int node,int bas,int son,int x) {
if(bas>x || son<x) return -1;
if(bas>=x && son<=x) return S[node];
push(node);
return max(get(node<<1,bas,orta,x),get(node<<1|1,orta+1,son,x));
}
void up(int node,int bas,int son,int x,int y,int val) {
if(bas>y || son<x) return ;
if(bas>=x && son<=y) {
shift(node,val);
return ;
}
push(node);
up(node<<1,bas,orta,x,y,val);
up(node<<1|1,orta+1,son,x,y,val);
S[node]=max(S[node<<1],S[node<<1|1]);
}
int main() {
scanf("%d %d %d %d",&n,&m,&d,&k);
for(int i=1;i<=n;i++) {
scanf("%s",s+1);
for(int j=1;j<=m;j++) {
if(s[j]=='M') {
M[j].pb(i);
}
else if(s[j]=='S') {
int l=max(1,j-d);
int r=min(m,j+d);
int u=max(1,i-d);
int dd=min(n,i+d);
L[l].pb({u,dd,1});
L[r+1].pb({u,dd,-1});
}
}
}
for(int i=1;i<=m;i++) {
for(auto x:L[i]) up(1,1,n,x.l,x.r,x.v);
for(auto x:M[i]) ans+=(get(1,1,n,x)>=k);
}
printf("%d",ans);
}
