https://cses.fi/paste/b08757275bc1f3fcab886/
#4 n=int(input()) lst=list(map(int,input().split())) count=0 for i in range(1,n): t=lst[i]-lst[i-1] if t<0: count+=(-1*t) lst[i]=lst[i-1] print(count)
https://cses.fi/paste/b08757275bc1f3fcab886/
#4 n=int(input()) lst=list(map(int,input().split())) count=0 for i in range(1,n): t=lst[i]-lst[i-1] if t<0: count+=(-1*t) lst[i]=lst[i-1] print(count)