#include<bits/stdc++.h> #define int long long using namespace std; namespace Fast{ //注:快读快写与CCF函数不能一起用，不然可能会趋势 inline int fr(){ register int x = 0,f = 1; static char c = getchar(); while (c < '0' || c > '9'){ if (c == '-'){ f = -1; } c = getchar(); } while (c >= '0' && c <= '9'){ x = (x << 1) + (x << 3) + (c ^ 48); c = getchar(); } return x * f; } inline void fw(int x){ if (x == 0){ putchar('0'); return ; } if (x < 0){ putchar('-'); x = -x; } stack <char> s; while (x){ s.push(x % 10 + 48); x /= 10; } while (!s.empty()){ putchar(s.top()); s.pop(); } } inline void DEBUG(){ puts("awa"); } inline void CCF(){ //原来想叫CINCOUTFASTER的结果发现缩写竟然是CCF(doge) ios::sync_with_stdio(false); cin.tie(0),cout.tie(0); } } using namespace Fast; int n,maxn; char a[10][10]; bool res[10][10]; void dfs(int x,int y,int sum){ if (y > n){ dfs(x + 1,1,sum); return ; } if (x > n){ bool f = true; for (int i = 1;i <= n;i++){ bool fl = false; for (int j = 1;j <= n;j++){ if (res[i][j] && fl){ f = false; } if (res[i][j]){ fl = true; } else if (a[i][j] == 'X'){ fl = false; } } } if (!f){ return ; } for (int i = 1;i <= n;i++){ bool fl = false; for (int j = 1;j <= n;j++){ if (res[j][i] && fl){ f = false; } if (res[j][i]){ fl = true; } else if (a[j][i] == 'X'){ fl = false; } } } if (!f){ return ; } maxn = max(maxn,sum); return ; } res[x][y] = false; dfs(x,y + 1,sum); if (a[x][y] != 'X'){ res[x][y] = true; dfs(x,y + 1,sum + 1); res[x][y] = false; } } signed main(){ while (cin>>n){ if (n == 0){ break; } for (int i = 1;i <= n;i++){ for (int j = 1;j <= n;j++){ cin>>a[i][j]; } } maxn = 0; dfs(1,1,0); cout<<maxn<<'\n'; } return 0; }