
int main()
{
    int n,i,j,m,s,t;
    char a[102][102],b[102][102];
    scanf("%d",&n);

/*  ??????????????????????
	for(i=1;i<=n;i++){     
		for(j=1;j<=n;j++){
			scanf("%c",&(a[i][j]));
		}
	}
*/
//??????????????????????
	for(i=1;i<=n;i++){     
		scanf("%s",&(a[i][1]));  //?????????
	}

    scanf("%d",&m);
    for(j=0;j<n+2;j++){
        a[0][j]='#';
        a[n+1][j]='#';
    }
    for(i=0;i<n+2;i++){
        a[i][0]='#';
        a[i][n+1]='#';
    }
    for(s=2;s<=m;s++){
        for(i=1;i<=n;i++){
           for(j=1;j<=n;j++){   //???????????????a????????b??????????b??????????
               //if(a[i][j]=='@'){   
                   b[i][j]=a[i][j];
               //}
           }
        }
        for(i=1;i<=n;i++){
           for(j=1;j<=n;j++){
               if(b[i][j]=='@'){
                   if(a[i][j+1]!='#'){
                       a[i][j+1]='@';   
                   }
                   if(a[i][j-1]!='#'){
                       a[i][j-1]='@';  
                   }
                   if(a[i+1][j]!='#'){
                       a[i+1][j]='@';   
                   }
                   if(a[i-1][j]!='#'){
                       a[i-1][j]='@';   
                   }
               }
            }
         }
     }
    t=0;
    for(i=0;i<=n+1;i++){
        for(j=0;j<=n+1;j++){
            if(a[i][j]=='@'){
                t=t+1;
            }
        }
    }
    printf("%d",t);
    return 0;
}

