Question 4
Given four distinct non-zero digits $a,b,c$ and $d$, if $\overline{ab}+\overline{cd}=\overline{dc}+\overline{ba}$, then this expression is called a palindrome expression and the sum of the two numbers $\overline{ab}+\overline{cd}$ is called a palindrome sum. For example, $53+46=64+35=99$. What is the minimum possible value of a palindrome sum?