error[E0716]: temporary value dropped while borrowed
  --> answer.code:60:21
   |
60 |             let m = [a, b, c].into_iter().min().unwrap();
   |                     ^^^^^^^^^                           - temporary value is freed at the end of this statement
   |                     |
   |                     creates a temporary value which is freed while still in use
61 |             let m = m + 0;
   |                     - borrow later used here
   |
   = note: consider using a `let` binding to create a longer lived value

error: aborting due to previous error

For more information about this error, try `rustc --explain E0716`.