import std.conv, std.functional, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.complex, std.container, std.math, std.numeric, std.range, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } real readReal() { return readToken.to!real; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; } int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); } int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); } enum DX = [[+2, +1, -1, -2, -2, -1, +1, +2], [+1, -1, -1, +1]]; enum DY = [[+1, +2, +2, +1, -1, -2, -2, -1], [+1, +1, -1, -1]]; int H, W; string[] S; void main() { try { for (; ; ) { H = readInt(); W = readInt(); S = new string[H]; foreach (x; 0 .. H) { S[x] = readToken(); } auto q = DList!int(); auto d = new int[][][](H, W, 2); foreach (x; 0 .. H) foreach (y; 0 .. W) { d[x][y][] = H * W * 2; } foreach (x; 0 .. H) foreach (y; 0 .. W) { if (S[x][y] == 'S') { d[x][y][0] = 0; q.insertBack(x); q.insertBack(y); q.insertBack(0); } } int ans = -1; for (; !q.empty; ) { const x = q.front; q.removeFront; const y = q.front; q.removeFront; const z = q.front; q.removeFront; const c = d[x][y][z]; if (S[x][y] == 'G') { ans = c; break; } /* foreach (dir; 0 .. DX[z].length) { const xx = x + DX[z][dir]; const yy = y + DY[z][dir]; if (0 <= xx && xx < H && 0 <= yy && yy < W) { const zz = (S[xx][yy] == 'R') ? (z ^ 1) : z; if (chmin(d[xx][yy][zz], c + 1)) { q.insertBack(xx); q.insertBack(yy); q.insertBack(zz); } } } */ void check(int xx, int yy) { const zz = (S[xx][yy] == 'R') ? (z ^ 1) : z; if (chmin(d[xx][yy][zz], c + 1)) { q.insertBack(xx); q.insertBack(yy); q.insertBack(zz); } } switch (z) { case 0: { if (x + 1 < H) { if (y + 2 < W) check(x + 1, y + 2); if (y - 2 >= 0) check(x + 1, y - 2); if (x + 2 < H) { if (y + 1 < W) check(x + 2, y + 1); if (y - 1 >= 0) check(x + 2, y - 1); } } if (x - 1 >= 0) { if (y + 2 < W) check(x - 1, y + 2); if (y - 2 >= 0) check(x - 1, y - 2); if (x - 2 >= 0) { if (y + 1 < W) check(x - 2, y + 1); if (y - 1 >= 0) check(x - 2, y - 1); } } } break; case 1: { if (x + 1 < H) { if (y + 1 < W) check(x + 1, y + 1); if (y - 1 >= 0) check(x + 1, y - 1); } if (x - 1 >= 0) { if (y + 1 < W) check(x - 1, y + 1); if (y - 1 >= 0) check(x - 1, y - 1); } } break; default: assert(false); } } writeln(ans); } } catch (EOFException e) { } }