public int numberOfWays(String corridor) {
        int n = corridor.length();
        int s = 0;
        long ans = 1;
        int loc = 1;
        boolean flag = false;
        int i = 0;
        while (i < n) {
            if (corridor.charAt(i++) == 'S') {
                s++;
                break;
            }
        }
        for (; i < n; i++) {
            char chr = corridor.charAt(i);
            if (chr == 'S') {
                s++;
                if (flag) {
                    ans = (ans * loc) % 1000000007;
                    loc = 1;
                }
                flag = !flag;
            } else {
                if (flag) {
                    loc++;
                }
            }
        }
        if (s == 0 || s % 2 == 1) return 0;
        return (int)ans;
    }