int main(){
	int n,i,j,k,m,result=0;
	char s[101][101],s1[101][101],s2[101][101];
	scanf("%d",&n);
	for(i=0;i<n;i++){
			scanf("%s",&s[i]);
	}
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			s1[i+1][j+1]=s[i][j];
			s2[i][j]=s[i][j];
		}
	}
	scanf("%d",&m);
    for(i=0;i<=n+1;i++){
		for(j=0;j<=n+1;j++){
			if(i==0||i==n+1||j==0||j==n+1){
				s1[i][j]='#';
			}
		}
	}
	for(k=1;k<m;k++){
	    for(i=1;i<=n;i++){
		    for(j=1;j<=n;j++){
			    if(s1[i][j]=='@'){
					s2[i-1][j-1]='@';
				    if(s1[i-1][j]!='#'){
					    s2[i-2][j-1]='@';
					}if(s1[i+1][j]!='#'){
					    s2[i][j-1]='@';
					}if(s1[i][j-1]!='#'){
					    s2[i-1][j-2]='@';
					}if(s1[i][j+1]!='#'){
					    s2[i-1][j]='@';
					}
				}
			}
		}
		for(i=0;i<n;i++){
			for(j=0;j<n;j++){
				if(s2[i][j]=='@'){
					s1[i+1][j+1]=s2[i][j];
				}
			}
		}
	}
	for(i=0;i<n;i++){
		for(j=0;j<n;j++){
			if(s2[i][j]=='@'){
				result++;
			}
		}
	}
	printf("%d",result);
	return 0;
}