Redundant Array

Chef has an array $A$ containing $N$ positive integers. He can perform the following operation on the array as many times as he likes: - Choose integers $L$ and $R$ such that $1 \leq L \leq R \leq N$; - Choose a **positive** integer $x$; - For every index $i$ from $L$ to $R$ (inclusive of both), set $A_i = x$. The cost of such an operation is $(R-L+1) \cdot x$. Find the **minimum cost** requir