1490

#include <bits/stdc++.h>
#define MAX 100007

using namespace std;

struct edge{
    int to, cap, rev;

    edge(int _to, int _cap, int _rev): to(_to), cap(_cap), rev(_rev){}
};

struct dinic{
    int INF;
    vector<edge> graph[MAX];
    int level[MAX], iter[MAX];

    dinic(){
        INF = 1e9 + 7;
        fill(level, level+MAX, 0);
        fill(iter, iter+MAX, 0);
        fill(graph, graph+MAX, vector<edge> ());
    }

    void add(int from, int to, int cap){
        graph[from].push_back(edge(to, cap, graph[to].size()));
        graph[to].push_back(edge(from, 0, graph[from].size()-1));
    }

    void bfs(int s){
        memset(level, -1, sizeof level);
        queue<int> q;
        level[s] = 0;
        q.push(s);

        while(!q.empty()){
            int actual = q.front();
            q.pop();

            for(int i = 0; i < graph[actual].size(); i++){
                edge &e = graph[actual][i];
                if(e.cap > 0 && level[e.to] < 0){
                    level[e.to] = level[actual] + 1;
                    q.push(e.to);
                }
            }
        }
    }

    int dfs(int v, int t, int f){
        if(v == t) return f;

        for(int &i = iter[v]; i < graph[v].size(); i++){
            edge &e = graph[v][i];
            if(e.cap > 0 && level[v] < level[e.to]){
                int d = dfs(e.to, t, min(f, e.cap));
                if(d > 0){
                    e.cap -= d;
                    graph[e.to][e.rev].cap += d;
                    return d;
                }
            }
        }
        return 0;
    }

    int flow(int start, int to){
        int ans = 0;
        while(true){
            bfs(start);
            if(level[to] < 0) return ans;
            memset(iter, 0, sizeof iter);
            int f;
            while((f = dfs(start, to, INF)) > 0) ans += f;

        }
    }
};

int linha[2][MAX], coluna[2][MAX];
int main(){
    int n;
    while(scanf("%d", &n) != EOF){
        int no = 2;
        memset(linha, 0, sizeof linha);
        memset(coluna, 0, sizeof coluna);
        for(int i = 0; i < n; i++) {
            linha[0][i] = no++;
            coluna[0][i] = no++;
        }

        dinic d = dinic();
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                char pos; scanf(" %c", &pos);
                if(pos == 'X'){
                    if(linha[1][i]) linha[0][i] = no++;
                    if(coluna[1][j]) coluna[0][j] = no++;
                }else{
                    linha[1][i] = 1;
                    coluna[1][j] = 1;
                    d.add(linha[0][i], coluna[0][j], 1);
                }
            }
        }

        for(int i = 2; i < no; i++){
            if(i%2 == 0) d.add(0, i, 1);
            else d.add(i, 1, 1);
        }

        printf("%d\n", d.flow(0,1));
    }
    return 0;
}