4. M={2. 13. 25. 44}
M₁={2, 13. 44}
M₂=2,13,25}
M₃={13,44,25}
M₄={2,44,25}
5. M₁={1,2,3,4}
M₂={4,5,7,8}
M₃={2,3,4,5}