A block of mass $1\mathrm{.}79$ kg is placed on a frictionless floor and initially pushed northward, whereupon it begins sliding with a constant speed of $5\mathrm{.}58$ m$/$s$.$ It eventually collides with a second, stationary block, of mass $3\mathrm{.}55$ kg$,$ head$-$on$,$ and rebounds back to the south. The collision is $100\%$ elastic. What will be the speeds of the $1\mathrm{.}79-$kg and $3\mathrm{.}55-$kg blocks, respectively, after this collision?