prove correctness of algorithm based on loop invariant . please show how to do this in very easy to understand steps. i am very confused and unsure of how to begin

Correctness proof (bubble son based on loop invariant *Stale loop inveniunt in proof Algorithm: Bubble Sort (A[o...n-1) // Sovts given unuy by bubble sort Il input an array Aco..n- of orderuble elements dloutput: Array A Co.n- sonled in nondecreasing order for ito to n-2 do for jEo to n-2-i do if A[j + i]