There are ten boys $\mathrm{B}_1, \mathrm{~B}_2, \ldots ., \mathrm{B}_{10}$ and five girls $\mathrm{G}_1, \mathrm{G}_2, \ldots ., \mathrm{G}_5$ in a class. Then the number of ways of forming a group consisting of three boys and three girls, if both $\mathrm{B}_1$ and $\mathrm{B}_2$ together should not be the members of a group, is $\_\_\_\_$ .