#include <iostream>
#include<vector>
#include<string>
#include<map>
using namespace std;
int main() {
int n, m;
cin>>n>>m;
int k;
cin>>k;
vector<string> mat(n, "");
map<int, vector<int>> cols;
map<int, vector<int>> rows;
for(int i=0;i<n;i++){
string s;
cin>>s;
mat[i] = s;
}
for(int i=0;i<n;i++){
for(int j=0;j<m;j++){
if(mat[i][j] == 'B'){
vector<int> temp;
if(cols.find(j) != cols.end()){
temp = cols[j];
}
temp.push_back(i);
cols[j] = temp;
vector<int> temp2;
if(rows.find(i) != rows.end()){
temp2 = rows[i];
}
temp2.push_back(j);
rows[i] = temp2;
}
}
}
int ans = 0;
for(int i=0;i<m;i++){
if(cols[i].size() != k )continue;
string cmp = "";
bool match = true;
for(int j=0;j<cols[i].size();j++){
if(rows[cols[i][j]].size() != k){
match=false;
break;
}
if(cmp == "")cmp = mat[cols[i][j]];
else if(cmp != mat[cols[i][j]]){
match = false;
break;
}
}
if(match == true){
ans += k;
}
}
cout<<ans<<endl;
}
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