Array Game

Alice has an array $A$ and Bob an array $B$ of sizes $N$ and $M$ respectively. Alice wants every value of her array to be greater than or equal to the values of Bob's array. In other words for every pair $(i ,j)$ $A[ i ] \geq B[ j ]$. In one operation she can increase or decrease any element of array $A$ or array $B$ by 1. Since she is always in a hurry he wants to perform this in minimum op