#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
#define fi first
#define se second

const int maxn = 512;
int h, w, dis[maxn][maxn], ans, cur;
pii par[maxn][maxn], spec[maxn][maxn];
vector<pii> al[maxn][maxn];
string board[maxn*2];

void dfs(pii node){
	for(int i=0; i<al[node.fi][node.se].size(); i++){
		pii to = al[node.fi][node.se][i];
		if(to != par[node.fi][node.se]){
			dis[to.fi][to.se] = dis[node.fi][node.se] + 1;
			par[to.fi][to.se] = node;
			dfs(to);
		}
	}
}

void dfspec(pii node){
	if(spec[node.fi][node.se] == make_pair(-1, -1)){
		pii temp = par[node.fi][node.se];
		dfspec(temp);
		spec[node.fi][node.se] = spec[temp.fi][temp.se];
	}
}

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	cin >> h >> w;
	for(int i=0; i<=h*2; i++){
		cin >> board[i];
		if(i%2){
			for(int j=1; j<w; j++){
				if(board[i][j*2] == '.'){
					al[i/2][j-1].push_back({i/2, j});
					al[i/2][j].push_back({i/2, j-1});
				}
			}
		}else if(i!=0 && i!=h*2){
			for(int j=0; j<w; j++){
				if(board[i][j*2+1] == '.'){
					al[i/2-1][j].push_back({i/2, j});
					al[i/2][j].push_back({i/2-1, j});
				}
			}
		}
	}
	par[0][0] = {-1, -1};
	dfs({0,0});
	// init spesial
	for(int i=0; i<h; i++){
		for(int j=0; j<w; j++){
			spec[i][j] = {-1, -1};
		}
	}
	// jalan spesial
	pii cur = {h-1, w-1}; spec[cur.fi][cur.se] = cur;
	while(cur != make_pair(0, 0)){
		cur = par[cur.fi][cur.se];
		spec[cur.fi][cur.se] = cur;
	}
	// bukan special
	for(int i=0; i<h; i++){
		for(int j=0; j<w; j++){
			dfspec({i, j});
		}
	}

	ans = 0;
	//cout << ans << endl;

	for(int i=0; i<=h*2; i++){
		if(i%2){
			for(int j=1; j<w; j++){
				if(board[i][j*2] == '|'){
					//al[i/2][j-1].push_back({i/2, j});
					//al[i/2][j].push_back({i/2, j-1});
					pii temp0 = spec[i/2][j-1], temp1 = spec[i/2][j];
					if(temp0 != temp1){
						ans = max(
							dis[i/2][j-1] - dis[temp0.fi][temp0.se] + dis[i/2][j] - dis[temp1.fi][temp1.se] 
							+ 1 - abs(dis[temp0.fi][temp0.se] - dis[temp1.fi][temp1.se]), ans
						);
					}
				}
			}
		}else if(i!=0 && i!=h*2){
			for(int j=0; j<w; j++){
				if(board[i][j*2+1] == '-'){
					//al[i/2-1][j].push_back({i/2, j});
					//al[i/2][j].push_back({i/2-1, j});
					pii temp0 = spec[i/2-1][j], temp1 = spec[i/2][j];
					if(temp0 != temp1){
						ans = max(
							dis[i/2-1][j] - dis[temp0.fi][temp0.se] + dis[i/2][j] - dis[temp1.fi][temp1.se] 
							+ 1 - abs(dis[temp0.fi][temp0.se] - dis[temp1.fi][temp1.se]), ans
						);
					}
				}
			}
		}
	}
	cout << ans + dis[h-1][w-1] + 1 << endl;
	return 0;
}