1 /*
 2  *Author:       Zhaofa Fang
 3  *Created time: 2013-03-23-21.36
 4  *Language:     C++
 5  */
 6 #include <cstdio>
 7 #include <cstdlib>
 8 #include <sstream>
 9 #include <iostream>
10 #include <cmath>
11 #include <cstring>
12 #include <algorithm>
13 #include <string>
14 #include <utility>
15 #include <vector>
16 #include <queue>
17 #include <stack>
18 #include <map>
19 #include <set>
20 using namespace std;
21
22 typedef long long ll;
23 #define DEBUG(x) cout<< #x << ':' << x << endl
24 #define REP(i,n) for(int i=0;i < (n);i++)
25 #define REPD(i,n) for(int i=(n-1);i >= 0;i--)
26 #define FOR(i,s,t) for(int i = (s);i <= (t);i++)
27 #define FORD(i,s,t) for(int i = (s);i >= (t);i--)
28 #define PII pair<int,int>
29 #define PB push_back
30 #define MP make_pair
31 #define ft first
32 #define sd second
33 #define lowbit(x) (x&(-x))
34 #define INF (1<<30)
35
36 int n,m;
37 int C[2011][2011];
38 char str[2011][2011];
39
40
41 void fun(){
42     C[0][0] = 0;
43     FOR(i,1,n){
44         C[i][0] = 0;
45         FOR(j,1,m){
46             C[i][j] = C[i][j-1]+(str[i][j]=='*'?1:0);
47         }
48     }
49     FOR(i,2,n){
50         FOR(j,1,m){
51             C[i][j] += C[i-1][j];
52         }
53     }
54 }
55 int Area(int x1,int y1,int x2,int y2){
56     if(x1>x2)swap(x1,x2);
57     if(y1>y2)swap(y1,y2);
58     return C[x2][y2]-C[x2][y1-1]-C[x1-1][y2]+C[x1-1][y1-1];
59 }
60
61  int main()
62 {
63      //freopen("in","r",stdin);
64      //freopen("out","w",stdout);
65      while(~scanf("%d%d",&n,&m),n,m){
66         int x,y;
67         scanf("%d%d",&x,&y);
68         FOR(i,1,n)scanf("%s",str[i]+1);
69         fun();
70         int ans = 0;
71         FOR(i,1,n){
72             FOR(j,1,m){
73                 if(str[i][j] != '*')continue;
74                 int xx1 = i+x-1;
75                 int yy1 = j+y-1;
76                 if(!(xx1<1||yy1<1||xx1>n||yy1>m)){
77                     if(Area(i,j,xx1,yy1) == x*y)ans++;
78
79                 }
80
81                 int xx2 = i+y-1;
82                 int yy2 = j+x-1;
83                 if(xx2 == xx1 && yy2==yy1)continue;
84                 if(xx2<1||yy2<1||xx2>n||yy2>m)continue;
85                 if(Area(i,j,xx2,yy2) == x*y)ans++;
86
87             }
88         }
89         printf("%d\n",ans);
90      }
91      return 0;
92  }