a_0 \exp\left( - Y_0 \right) \: - \: b_0 \exp\left( - \tilde{Y}_0 \right) \right] \nonumber \\ & &  \: - \: \tilde{F}_0 \left[ q_0 \exp\left( + \tilde{Y}_0 \right) \: - \: c_0 \exp\left( - Y_0 \right) \