How many ${\mathrm{H}}^{+}$ ions are required when the equation below is balanced with the smallest whole number coefficients?

$\begin{array}{l}\mathrm{Cu}\left(s\right)+{\mathrm{NO}}_3^{-}\left(aq\right)+{\mathrm{H}}^{+}\left(aq\right)⟶{\mathrm{Cu}}^{2+}\left(aq\right)+\mathrm{NO}\left(g\right)+\\ {\mathrm{H}}_2\mathrm{O}\left(l\right)\end{array}$