package no043;

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;
import java.util.TreeSet;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		char[][] map = new char[n][];
		char[][] map2 = new char[n][n];
		for(int i=0;i<n;i++) {
			map[i] = sc.next().toCharArray();
		}
		int m = n * (n - 1) / 2;
		int[] wins = new int[n];
		int ans = 999;
		LOOP: for(int i=0;i<1<<m;i++) {
			int ni = 0;
			int nj = 1;
			for(int j=0;j<m;j++) {
				map2[ni][nj] = ((i>>j) & 1) == 0 ? 'x' : 'o' ;
				if (nj == n-1) {
					ni++;
					nj = ni + 1;
				}else{
					nj++;
				}
			}
			//矛盾のチェック
			for(int i2=0;i2<n;i2++) {
				for(int j2=i2+1;j2<n;j2++) {
					if (map[i2][j2] != '-' && map[i2][j2] != map2[i2][j2]) {
						continue LOOP;
					}
				}
			}
			//完全な順位表の作成
			for(int i2=0;i2<n;i2++) {
				for(int j2=0;j2<=i2;j2++) {
					if (i2 == j2) {
						map2[i2][j2] = '#';
					}else{
						map2[i2][j2] = map2[j2][i2] == 'o' ? 'x' : 'o';
					}
				}
			}
			//集計
			Arrays.fill(wins, 0);
			TreeSet<Integer> ts = new TreeSet<>(Collections.reverseOrder());
			for(int i2=0;i2<n;i2++) {
				for(int j2=0;j2<n;j2++) {
					if (map2[i2][j2] == 'o') {
						wins[i2]++;
					}
				}
				ts.add(wins[i2]);
			}
			int rank = 1;
			for(Integer x:ts) {
				if (x == wins[0]) {
					break;
				}
				rank++;
			}
			ans = Math.min(ans,rank);
		}
		System.out.println(ans);
	}

}
class Pair<A extends Comparable<A>,B extends Comparable<B>> implements Comparable<Pair<A,B>>{
	A a;
	B b;
	public Pair(A a,B b) {
		this.a = a;
		this.b = b;
	}
	public int compareTo(Pair<A, B> o) {
		int comp = a.compareTo(o.a);
		if (comp != 0) {
			return comp;
		}
		return b.compareTo(o.b);
	}
	public boolean equals(Object o) {
		if (o instanceof Pair) {
			@SuppressWarnings("rawtypes")
			Pair p = (Pair) o;
			return a.equals(p.a) && b.equals(p.b);
		}
		return super.equals(o);
	}
	public int hashCode() {
		return a.hashCode() + b.hashCode();
	}
	public String toString() {
		return "[" + a + "," + b + "]";
	}
	public static <C extends Comparable<C>,D extends Comparable<D>> Comparator<Pair<C,D>> CompareA() {
		Comparator<Pair<C,D>> comp = new Comparator<Pair<C,D>>() {
			public int compare(Pair<C, D> o1, Pair<C, D> o2) {
				int comp = o1.a.compareTo(o2.a);
				if (comp != 0) {
					return comp;
				}
				return o1.b.compareTo(o2.b);
			}
		};
		return comp;
	};
	public static <C extends Comparable<C>,D extends Comparable<D>> Comparator<Pair<C,D>> CompareB() {
		Comparator<Pair<C,D>> comp = new Comparator<Pair<C,D>>() {
			public int compare(Pair<C, D> o1, Pair<C, D> o2) {
				int comp = o1.b.compareTo(o2.b);
				if (comp != 0) {
					return comp;
				}
				return o1.a.compareTo(o2.a);
			}
		};
		return comp;
	};
}