HDU 4517

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;

const int N=2005;

int cn[N][N];
int n,m,x,y;
char str[N];

int main(){
    while(scanf("%d%d",&n,&m),n||m){
        scanf("%d%d",&x,&y);
        for(int i=0;i<=n;i++){
            for(int j=0;j<=m;j++)
            cn[i][j]=0;
        }
        int ans=0;
        for(int i=1;i<=n;i++){
            scanf("%s",str+1);
            for(int j=1;j<=m;j++)
            if(str[j]==‘*‘){
                cn[i][j]=cn[i-1][j]+cn[i][j-1]-cn[i-1][j-1]+1;
                if(i-x>=0&&j-y>=0){
                    ans+=(cn[i][j]-cn[i-x][j]-cn[i][j-y]+cn[i-x][j-y])==x*y?1:0;
                }
                if(i-y>=0&&j-x>=0&&x!=y){
                    ans+=(cn[i][j]-cn[i-y][j]-cn[i][j-x]+cn[i-y][j-x])==x*y?1:0;
                }
            }
            else cn[i][j]=cn[i-1][j]+cn[i][j-1]-cn[i-1][j-1];
        }
        printf("%d\n",ans);
    }
    return 0;
}