If ${\left\{{\mathrm{a}}_{\mathrm{i}}\right\}}_{\mathrm{i}=1}^{\mathrm{n}}$where n is an even integer , is an arithmetic progression with common difference 1,and   $\sum _{\mathrm{i}=1}^{\mathrm{n}} {\mathrm{a}}_{\mathrm{i}}=192,\sum _{\mathrm{i}=1}^{\mathrm{n}/2} {\mathrm{a}}_{2\mathrm{i}}=120$ then n is equal to: