#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define IO ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define PII pair<int, int>
const LL N = 200 + 10;
const LL INF = 0x3f3f3f3f;
const int P = 131;
const ULL MOD = ULONG_LONG_MAX;

int n, ans;
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};
bool vis[N][N];
char s[N][N];

bool flag(int x, int y) {
	return (x > n || y > n || x < 1 || y < 1 || vis[x][y] || s[x][y] == 'X');
}

void dfs(int x, int y, int sum) {
	if(s[x][y] == '$') {
		++sum;
		ans = max(ans, sum);
	}
	for(int i = 0; i < 4; i++) {
		int nx = x + dx[i];
		int ny = y + dy[i];
		if(!flag(nx,ny))
			vis[nx][ny] = 1, dfs(nx, ny, sum);
	}
}

signed main() {
    // IO;
    cin >> n;
	for(int i = 1; i <= n; i++)
		scanf("%s", s[i]+1);
	for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= n; j++) {
            if(!vis[i][j] && s[i][j] != 'X')
				dfs(i, j, 0);
        }
    }
	cout << ans << endl;
    return 0;
}