private boolean oneExit() {
        int j = 0;
        if(getNExit() != null)
            j++;
        if(getSExit() != null)
            j++;
        if(getEExit() != null)
            j++;
        if(getWExit() != null)
            j++;
        if(j == 1)
            return true;
        return false;
    }