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#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#define N 150
#define V 1000
typedef struct { int i, j; } node_t;
typedef struct { int u, w; } edge_t;
int d[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
bool v[N][N];
char map[N][N];
int n, s, t, nv, ne[V];
node_t node[V];
edge_t g[V][4];
int max(int x, int y) { return x > y ? x : y; }
bool isjunc(int i, int j) {
int nn = 0;
for (int k = 0; k < 4; k++)
nn += map[i+d[k][0]][j+d[k][1]] == '#';
return nn != 2;
}
void advance(int io, int jo, int *i, int *j) {
for (int k = 0; k < 4; k++) {
int ni = *i + d[k][0], nj = *j + d[k][1];
if (!v[ni][nj] && (ni != io || nj != jo) &&
map[ni][nj] != '#') {
*i = ni;
*j = nj;
if (!isjunc(*i, *j)) v[*i][*j] = true;
return;
}
}
}
int findorcreate(int i, int j) {
for (int u = 0; u < nv; u++)
if (node[u].i == i && node[u].j == j)
return u;
node[nv] = (node_t) {.i = i, .j = j};
return nv++;
}
edge_t findedge(int io, int jo, int i, int j) {
int w;
v[i][j] = true;
for (w = 1; !isjunc(i, j); w++) advance(io, jo, &i, &j);
return (edge_t) {.u = findorcreate(i, j), .w = w};
}
void makegraph(int u) {
int i = node[u].i, j = node[u].j;
for (int k = 0; k < 4; k++) {
int ni = i + d[k][0], nj = j + d[k][1];
if (!v[ni][nj] && map[ni][nj] != '#') {
edge_t e = findedge(i, j, ni, nj);
g[u][ne[u]++] = (edge_t) {.u = e.u, .w = e.w};
g[e.u][ne[e.u]++] = (edge_t) {.u = u, .w = e.w};
}
}
}
int longpath(int u) {
int i = node[u].i, j = node[u].j, k, ret, p;
if (i == n-1 && j == t) return 0;
if (v[i][j]) return -1;
v[i][j] = true;
for (ret = -1, k = 0; k < ne[u]; k++)
if ((p = longpath(g[u][k].u)) != -1)
ret = max(ret, g[u][k].w + p);
v[i][j] = false;
return ret;
}
int main() {
for (n = 1; fgets(map[n], N, stdin) != NULL; n++) ;
memset(map[0], '#', n);
memset(map[n], '#', n);
for (int i = 0; i < n; i++) if (map[1][i] == '.') s = i;
for (int i = 0; i < n; i++) if (map[n-1][i] == '.') t = i;
findorcreate(1, s);
for (int u = 0; u < nv; u++)
makegraph(u);
printf("%d\n", longpath(0));
return 0;
}
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