#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
//using mint = modint998244353;
int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    ll h,w;
    cin >> h >> w;

    vector<string> mass(h);

    for(ll i = 0; i < h; i++){
        cin >> mass[i];
    }

    ll ans = h+w;
    vector<ll> dx = {1,0,-1,0};
    vector<ll> dy = {0,1,0,-1};
    vector<vector<bool>> come(h,vector<bool>(w,0));
    queue<ll> que;

    ll maxx = 0;
    ll maxy = 0;
    que.push(0);
    come[0][0] = 1;
    while(!que.empty()){
        ll x = que.front() / 10000;
        ll y = que.front() % 10000;
        que.pop();

        for(ll i = 0; i < 2; i++){
            ll xx = x + dx[i];
            ll yy = y + dy[i];
            if(xx >= h)continue;
            if(yy >= w)continue;
            if(come[xx][yy])continue;
            if(mass[xx][yy] == '#')continue;
            come[xx][yy] = 1;
            maxx = max(maxx,xx);
            maxy = max(maxy,yy);
            que.push(xx * 10000 + yy);
        }
    }

    if(come[h-1][w-1])ans -= 2;
    else{
        ll minx = h-1;
        ll miny = w-1;
        que.push((h-1)*10000 + w-1);
        come[h-1][w-1] = 1;
        while(!que.empty()){
            ll x = que.front() / 10000;
            ll y = que.front() % 10000;
            que.pop();

            for(ll i = 2; i < 4; i++){
                ll xx = x + dx[i];
                ll yy = y + dy[i];
                if(xx < 0)continue;
                if(yy < 0)continue;
                if(come[xx][yy])continue;
                if(mass[xx][yy] == '#')continue;
                come[xx][yy] = 1;
                minx = min(minx,xx);
                miny = min(miny,yy);
                que.push(xx * 10000 + yy);
            }
        }

        if(minx - maxx < 2 || miny - maxy < 2)ans--;
    }

    cout << ans << '\n';

}