#include <stdio.h>

char field[5][5];
int size;
int max;

bool cols[5];
bool rows[5];

void Draw() {
    for(int i = 0; i < size; i++) {
	for(int j = 0; j < size; j++) 
	    printf("%c", field[i][j]);
	printf("\n");
    }
}

bool Validate() {
    int count = 0;
    for(int i = 0; i < size; i++) {
	cols[i] = false;
	rows[i] = false;
    }
    for(int i = 0; i < size; i++) {
	for(int j = 0; j < size; j++) {
	    if(field[i][j] == '1' && !cols[j] && !rows[i]) {
		count++; 
		cols[j] = true;
		rows[i] = true;
		continue;
	    }
	    if(field[i][j] == '1' && (cols[j] || rows[i])) return false;
	    if(field[i][j] == 'X') {
		rows[i] = false;
		cols[j] = false;
	    }
	}
    }
    if (count > max) max = count;
    return true;
}

void Solve(int row = 0, int col = 0) {
    if (col < size-1)
	Solve(row, col+1);
    if (col == size-1 && row < size-1)
        Solve(row+1, 0);
    Validate();
    if (field[row][col] == '.') {
	field[row][col] = '1';
	Validate();
	if (col < size-1)
	    Solve(row, col+1);
        if (col == size-1 && row < size-1)
	    Solve(row+1, 0);
	field[row][col] = '.';
//	Validate();
    }
}

int main() {
    scanf("%d\n", &size);
    while(size) {
	for(int i = 0; i < size; i++) {
	    scanf("%s\n", field[i]);
	}
	max = 0;
//	Draw();
	Solve();
	printf("%d\n", max);
        scanf("%d\n", &size);
    }
    return 0;
}