/* -*- coding: utf-8 -*-
 *
 * 43.cc: No.43 野球の試合 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 6;
const int MAX_M = MAX_N * (MAX_N - 1) / 2;
typedef long long ll;

const int INF = 1 << 30;
const ll LINF = 1LL << 60;

/* typedef */

typedef vector<int> vi;
typedef queue<int> qi;
typedef pair<int,int> pii;

/* global variables */

string lines[MAX_N];
int gs[MAX_M][2], wins[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  cin >> n;

  for (int i = 0; i < n; i++) cin >> lines[i];

  int m = 0;
  for (int i = 0; i < n; i++)
    for (int j = i + 1; j < n; j++)
      gs[m][0] = i, gs[m][1] = j, m++;
  //printf("n=%d, m=%d\n", n, m);

  int mbits = 1 << m;
  int mini = n;
  
  for (int bits = 0; bits < mbits; bits++) {
    memset(wins, 0, sizeof(wins));
    bool ok = true;

    for (int i = 0; ok && i < m; i++) {
      int &i0 = gs[i][0], &i1 = gs[i][1];
      if ((bits >> i) & 1) {
	if (lines[i0][i1] == 'o') ok = false;
	else wins[i1]++;
      }
      else {
	if (lines[i0][i1] == 'x') ok = false;
	else wins[i0]++;
      }
    }
    if (! ok) continue;

    //for (int i = 0; i < n; i++) printf("%d", wins[i]); putchar('\n');
    
    int w0 = wins[0];
    sort(wins, wins + n, greater<int>());
    int wn = unique(wins, wins + n) - wins;
    //printf("wn=%d\n", wn);

    for (int i = 0; i < wn; i++)
      if (wins[i] == w0 && mini > i) mini = i;
  }

  printf("%d\n", mini + 1);
  return 0;
}