Problem 1
There are 2026 integers greater than 1 written on a blackboard, not necessarily different. In one move, Confucius chooses two integers (m>1) and (n>1) from different positions on the blackboard and replaces them by
[ \gcd(m,n) \qquad\text{and}\qquad \frac{\operatorname{lcm}(m,n)}{\gcd(m,n)}. ]
He continues making moves for as long as this is possible.
- Prove that, regardless of Confucius's choices, after finitely many moves exactly one integer (M) on the blackboard is greater than 1.
- Prove that the value of (M) does not depend on Confucius's choices.
Here (\gcd(x,y)) denotes the greatest common divisor of positive integers (x,y), and (\operatorname{lcm}(x,y)) denotes their least common multiple.