#include <cstdio>

#define FOR(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define REV(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define INC(i, n) FOR(i, 0, n)
#define DEC(i, n) REV(i, 0, n)
#define INC1(i, n) FOR(i, 1, (n) + 1)
#define DEC1(i, n) REV(i, 1, (n) + 1)

typedef long long   signed int LL;
typedef long long unsigned int LU;


int n;
char s[6][6];
int pos[15], num;

int rank() {
	int win[6];
	INC(i, n) { int c = 0;
	INC(j, n) {
		if(s[i][j] == 'o') { c++; }
	} win[i] = c;
	}
	
	int ex[6];
	INC(i, 6) { ex[i] = 0; }
	INC(i, n) { ex[ win[i] ]++; }
	
	int r = 1;
	FOR(i, win[0] + 1, 6) { if(ex[i]) { r++; } }
	
	return r;
}

int main() {
	scanf("%d", &n);
	INC(i, n) { scanf("%s", s[i]); }
	
	INC(i, n) {
	INC(j, i) {
		if(s[i][j] == '-') { pos[num++] = i * n + j; }
	}
	}
	
	int best = 6;
	INC(i, 1 << num) {
		INC(j, num) {
			s[ pos[j] / n][ pos[j] % n] = ( i & (1 << j) ? 'o' : 'x');
			s[ pos[j] % n][ pos[j] / n] = ( i & (1 << j) ? 'x' : 'o');
		}
		int r = rank();
		if(best > r) { best = r; }
	}
	
	printf("%d\n", best);
	
	return 0;
}