import sys

from typing import List, Tuple

int1 = lambda x: int(x) - 1
input = lambda: sys.stdin.readline().rstrip('\n')
ii = lambda: int(input())
vi = lambda: list(map(int, input().split()))
vi1 = lambda: list(map(int1, input().split()))


def dbg(*args, **kwargs):
    print(*(repr(arg) for arg in args), *(f'{k}: {repr(v)}' for k, v in kwargs.items()),
          sep='; ', file=sys.stderr, flush=True)


def main():
    h, w = vi()
    c = [input() for _ in range(h)]
    fw = [[False] * w for _ in range(h)]
    bw = [[False] * w for _ in range(h)]

    for i in range(h):
        for j in range(w):
            if c[i][j] == '#':
                continue
            fw[i][j] = (c[i][j] == 'S') or (i > 0 and fw[i - 1][j]) or (j > 0 and fw[i][j - 1])

    for i in reversed(range(h)):
        for j in reversed(range(w)):
            if c[i][j] == '#':
                continue
            bw[i][j] = (c[i][j] == 'G') or (i < h - 1 and bw[i + 1][j]) or (j < w - 1 and bw[i][j + 1])

    if bw[0][0]:
        return h + w - 2

    fr = []
    br = []
    fc = []
    bc = []

    for i in range(h):
        fr.append(any(fw[i][j] for j in range(w)))
        br.append(any(bw[i][j] for j in range(w)))
        if fr[i] and br[i]:
            return h + w - 1

    for j in range(w):
        fc.append(any(fw[i][j] for i in range(h)))
        bc.append(any(bw[i][j] for i in range(h)))
        if fc[j] and bc[j]:
            return h + w - 1

    for i in range(h - 1):
        if (fr[i] and br[i + 1]) or (fr[i + 1] and br[i]):
            return h + w - 1

    for j in range(w - 1):
        if (fc[j] and bc[j + 1]) or (fc[j + 1] and bc[j]):
            return h + w - 1

    return h + w


def _start():
    if (ret := main()) is not None:
        print(*ret) if isinstance(ret, List) or isinstance(ret, Tuple) else print(ret)


if __name__ == '__main__':
    _start()