/**
	author:  shobonvip
	created: 2026.04.19 06:08:32
**/

#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)
#define all(v) v.begin(), v.end()

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
	int h, w;
	cin >> h >> w;
	vector<vector<char>> s(2 * h - 1, vector<char>(2 * w - 1, '.'));
	rep(i,0,h) rep(j,0,w) {
		cin >> s[2*i][2*j];
	}

	h = 2 * h - 1;
	w = 2 * w - 1;

	int sx = -1, sy = -1;
	int gx = -1, gy = -1;

	rep(i,0,h) {
		rep(j,0,w) {
			if (s[i][j] == 'S') {
				sx = i;
				sy = j;
			} else if (s[i][j] == 'G') {
				gx = i;
				gy = j;
			}
		}
	}

	deque<pair<int,int>> mada;
	vector d(h, vector<int>(w, 1e9));
	d[sx][sy] = 0;
	mada.emplace_back(sx, sy);
	while(!mada.empty()) {
		auto [i, j] = mada.front();
		mada.pop_front();
		for (auto [x, y]: {
			pair(i-1, j),
			pair(i+1, j),
			pair(i, j-1),
			pair(i, j+1)
		}) {
			if (!(0 <= x && x < h)) continue;
			if (!(0 <= y && y < w)) continue;
			if (s[x][y] == '#') continue;
			if (chmin(d[x][y], d[i][j] + 1)) {
				mada.emplace_back(x, y);
			}
		}

		if (i % 2 == 0) {
			for (auto [x, y]: {
				pair(i-2, j),
				pair(i+2, j)
			}) {
				if (!(0 <= x && x < h)) continue;
				if (s[x][y] == '#') continue;
				if (chmin(d[x][y], d[i][j] + 1)) {
					mada.emplace_back(x, y);
				}
			}
		}
		
		if (j % 2 == 0) {
			for (auto [x, y]: {
				pair(i, j-2),
				pair(i, j+2)
			}) {
				if (!(0 <= y && y < w)) continue;
				if (s[x][y] == '#') continue;
				if (chmin(d[x][y], d[i][j] + 1)) {
					mada.emplace_back(x, y);
				}
			}
		}
	}

	cout << d[gx][gy] << endl;
}