#include <iostream>
#include <fstream>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <typeinfo>

std::ifstream FileIn ("/home/habkaffee/Cpp/Islands/input.txt");
//std::ofstream FileOut ("/home/habkaffee/Cpp/Islands/out.txt");

long change (long cnt, std::vector<std::vector<long>> &array, long max, long min, int n){
    for (size_t i = 0; i<n ; ++i){
        if (array[0][i] == max){
            array[0][i] = min;
        }
        if (array[1][i] == max){
            array[1][i] = min;
        }
    }
    cnt++;
    return cnt;
}

int main(){
    int n = 0;
    FileIn >> n;
    std::vector<std::vector<long>> array (2,std::vector<long>(n,0));

//    std::cout << n;

    char temp = 0;

    for (size_t i = 0; i<n; ++i){
        FileIn >> temp;
        array[0][i] = temp == 'x' ? 0 : -1;
    }

   // std::cout<<std::endl;
    long counter = 0; //total num of islands.
    long cnt = 0; //total num of changed islands.

    for (size_t i = 0; i<n;++i){
        if (array[0][i] == 0){
            array[0][i] = counter+1;
            if (i>0){
                if (array[0][i-1] > 0){
                    array[0][i] = array[0][i-1];
                }
            }
            if (array[0][i] == counter+1){
                counter++;
            }
        }
    }


    for (int k = 1; k<n; k++){
        for (size_t i = 0; i<n; ++i){
            FileIn >> temp;
            array[1][i] = temp == 'x' ? 0 : -1;
        }

        for (size_t i = 0; i<n; ++i){
            if (array[1][i] == -1){
                continue;
            }
            else if (array[1][i] == 0){
                if (i > 0 && array[0][i]>0 && array[1][i-1]>0 && array[0][i] != array[1][i-1]){
                    array[1][i] = std::min(array[0][i], array[1][i-1]);
                    long a = std::max(array[0][i], array[1][i-1]);
                    cnt = change (cnt, array, a, array[1][i], n);
                }
                else if (array[0][i]>0){
                    array[1][i] = array[0][i];
                }
                else if (i>0 && array[1][i-1]>0) {
                    array[1][i] = array[1][i-1];
                }
                else{
                    counter++;
                    array[1][i] = counter;

                }
            }
        }

        array[0] = array[1];
        for (size_t i = 0; i<n;++i){
            array[1][i] = 0;
        }
    }

    std::cout<<counter-cnt<<std::endl;

    return 0;

}