#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n,m,k;
    cin>>n>>m>>k;
    vector<vector<char>> grid(n,vector<char>(m));
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            cin>>grid[i][j];
        }
    }
    vector<int> couts;
    for(int j=0;j<m;j++){
        int cnt=0;
        for(int i=0;i<n;i++){
            if(grid[i][j]=='*'){
                if(cnt !=0)
                couts.push_back(cnt);
                cnt=0;
            }
            else cnt++;
        }
        if(cnt !=0)
        couts.push_back(cnt);
    }
    sort(couts.begin(), couts.end(), greater<>());
    int score=0;
    for(int e:couts){
        int c=min(k,e);
        score+=c-1;
        k-=c;
        if(k<=0) break;
    }
    cout<<score<<endl;
    return 0;
}
// 64 位输出请用 printf("%lld")