If \(\rm\vec{a},\vec{b},\vec{c}\) are three vectors such that \(\rm\vec{a}+\vec{b}+\vec{c}=\vec{0}\) and \(\rm|\vec{a}|\) = 2, \(\rm|\vec{b}|\) = 3, \(\rm|\vec{c}|\) = 5, then value of \(\rm\vec{a}.\vec{b}+\vec{b}.\vec{c}+\vec{c}.\vec{a}\) is