#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = 1ll << 60;
#define REP(i, n) for(ll i =0; i < ll(n); i++)
template <class T> using V = vector<T>;
template <class A, class B>
bool chmax(A& a, B b) { return a<b && (a=b, true); }
template <class A, class B>
bool chmin(A& a, B b) { return b<a && (a=b, true); }

void testcase() {
  int h, w; cin >> h >> w;
  V<string> c(h);
  REP(i, h) cin >> c[i];
  auto dist_from = [&](int sx, int sy) {
    V dist(h, V<ll>(w, INF));
    queue<pair<int, int>> que;
    dist[sx][sy] = 0;
    que.emplace(sx, sy);
    constexpr int DX[4] = {1, 0, -1, 0};
    constexpr int DY[4] = {0, 1, 0, -1};
    while(!que.empty()) {
      auto [x, y] = que.front(); que.pop();
      REP(i, 4) {
        int nx = x+DX[i], ny = y+DY[i];
        if(nx < 0 || nx >= h || ny < 0 || ny >= w) continue;
        if(c[nx][ny] == '#') continue;
        if(chmin(dist[nx][ny], dist[x][y]+1)) {
          que.emplace(nx, ny);
        }
      }
    }
    return dist;
  };
  int sx = -1, sy = -1, gx = -1, gy = -1;
  REP(i, h) REP(j, w) {
    if(c[i][j] == 'S') {
      sx = i, sy = j;
    } else if(c[i][j] == 'G') {
      gx = i, gy = j;
    }
  }
  auto ds = dist_from(sx, sy);
  auto dg = dist_from(gx, gy);
  ll ans = ds[gx][gy];
  chmin(ans, h+w);
  REP(i, h-1) {
    ll tmp0 = INF, tmp1 = INF, tmp2 = INF, tmp3 = INF;
    REP(j, w) {
      chmin(tmp0, ds[i][j]-j);
      chmin(ans, dg[i+1][j]+j + tmp0 + 2);
      chmin(tmp1, dg[i][j]-j);
      chmin(ans, ds[i+1][j]+j + tmp1 + 2);
      chmin(tmp2, ds[i+1][j]-j);
      chmin(ans, dg[i][j]+j + tmp2 + 2);
      chmin(tmp3, dg[i+1][j]-j);
      chmin(ans, ds[i][j]+j + tmp3 + 2);
    }
  }
  REP(j, w-1) {
    ll tmp0 = INF, tmp1 = INF, tmp2 = INF, tmp3 = INF;
    REP(i, h) {
      chmin(tmp0, ds[i][j]-i);
      chmin(ans, dg[i][j+1]+i + tmp0 + 2);
      chmin(tmp1, dg[i][j]-i);
      chmin(ans, ds[i][j+1]+i + tmp1 + 2);
      chmin(tmp2, ds[i][j+1]-i);
      chmin(ans, dg[i][j]+i + tmp2 + 2);
      chmin(tmp3, dg[i][j+1]-i);
      chmin(ans, ds[i][j]+i + tmp3 + 2);
    }
  }
  cout << ans << '\n';
}

int main() {
  cin.tie(0)->sync_with_stdio(0);
  testcase();
}