Problem:
 Score : 300 points    Problem Statement N persons are standing in a row. The height of the i -th person from the front is A_i .  We want to have each person stand on a stool of some heights - at least zero - so that the following condition is satisfied for every person:  Condition: Nobody in front of the person is taller than the person. Here, the height of a person includes the stool.  Find the minimum total height of the stools needed to meet this goal.      Constraints  1 \leq N \leq 2\times 10^5  1 \leq A_i \leq 10^9  All values in input are integers.         Input Input is given from Standard Input in the following format:  N  A_1  \ldots  A_N       Output Print the minimum total height of the stools needed to meet the goal.        Sample Input 1 5
2 1 5 4 3      Sample Output 1 4  If the persons stand on stools of heights 0 , 1 , 0 , 1 , and 2 , respectively, their heights will be 2 , 2 , 5 , 5 , and 5 , satisfying the condition.  We cannot meet the goal with a smaller total height of the stools.       Sample Input 2 5
3 3 3 3 3      Sample Output 2 0  Giving a stool of height 0 to everyone will work.

Solution (Python):
def main():
    n = int(input())
    A = list(map(int, input().split()))
    ans, m = 0, 0
    for a in A:
        if a < m:
            ans += m - a
        else:
            m = a
    print(ans)


if __name__ == '__main__':
    main()

Solution (Python):
n = int(input())
a = list(map(int,input().split())) + [0]
ans = 0
maxh = a[0] 
for i in range(n):
    if maxh > a[i]:
        ans += maxh - a[i]
        a[i] = maxh
    else:
        maxh = a[i]
print(ans)

Solution (Python):
N, *A = map(int, open(0).read().split())

result = 0
p = A[0]
for i in range(1, N):
    if p >= A[i]:
        result += p - A[i]
    else:
        p = A[i]
print(result)

Solution (Python):
N = int(input())
A = list(map(int, input().split()))

ans = 0
mae = A[0]
for i in range(1, N):
    if mae > A[i]:
        ans += mae - A[i]
    else:
        mae = A[i]

print(ans)

Solution (Python):
n=int(input())
a=list(map(int,input().split()))
ans=0
for i in range(1,n):
    if a[i]<a[i-1]:
        ans+=a[i-1]-a[i]
        a[i]=a[i-1]
print(ans)

Solution (Python):
n = int(input())
A = list(map(int,input().split()))
big = A[0]
cnt = 0
for i in range (1,n):
    if A[i] < big:
        cnt += big-A[i]
    else:
        big = A[i]
print(cnt)

Solution (Python):
n=int(input())
a=list(map(int,input().split()))
r=0
for i in range (1,n):
    if a[i]<a[i-1]:
        r+=a[i-1]-a[i]
        a[i]=a[i-1]
print(r)

Solution (Python):
n = int(input())
a = list(map(int, input().split()))
ans = 0
num = a[0]
for i in range(n - 1):
    ans += max(num - a[i + 1], 0)
    num = max(num, a[i + 1])
print(ans)

Solution (Python):
n=int(input())
a=list(map(int,input().split()))
t=0
for i in range(n-1):
    x,y=a[i],a[i+1]
    if x>=y:
        a[i+1]=x
        t+=x-y
print(t)

Solution (Python):
n = int(input())
a = list(map(int, input().split()))

mx = a[0]
ans = 0
for i in range(1, n):
    if a[i] < mx:
        ans += mx - a[i]
    mx = max(mx, a[i])
print(ans)

Solution (Python):
n=int(input())
l=list(map(int,input().split()))
mx=l[0]
an=0
for i in range(1,n):
  if l[i]<mx:
    an+=mx-l[i]
  else:
    mx=l[i]
print(an)

Solution (Python):
import sys, bisect, math, itertools, heapq, collections
from operator import itemgetter

from functools import lru_cache

sys.setrecursionlimit(10**8)
input = sys.stdin.readline
INF = float('inf')
mod = 10**9 + 7
eps = 10**-7


def inp():
    '''
    一つの整数
    '''
    return int(input())


def inpl():
    '''
    一行に複数の整数
    '''
    return list(map(int, input().split()))


def str_inp():
    '''
    文字列をリストとして読み込む
    '''
    return list(input()[:-1])


n = inp()
a = inpl()
now = 0
ans = 0
for i in range(n):
    if now > a[i]:
        ans += now - a[i]
    else:
        now = a[i]
print(ans)

Solution (Python):
n=int(input())
A=list(map(int,input().split()))

num,height=0,A[0]
B=[]
for i in range(1,n):
    if height>A[i]:
        B.append(height-A[i])
        num=max(num,height-A[i])
    else:height=A[i]
print(sum(B))

Solution (Python):
import math
from collections import defaultdict
ml=lambda:map(int,input().split())
ll=lambda:list(map(int,input().split()))
ii=lambda:int(input())
ip=lambda:input()

"""========main code==============="""
t=1

for _ in range(t):
    n=ii()
    a=ll()
    ans=0
    for i in range(1,n):
        if(a[i]<a[i-1]):
            ans+=(a[i-1]-a[i])
            a[i]=a[i-1]
    print(ans)

Solution (Python):
def resolve():
    N = int(input())
    A = list(map(int, input().split()))
    hmax = A[0]
    total = 0
    for i in range(1, N):
        if hmax > A[i]:
            total += hmax-A[i]
        else:
            hmax = A[i]
    print(total)


if '__main__' == __name__:
    resolve()

Solution (Python):
n=int(input())
a=list(map(int,input().split()))
ans=0
for i in range(1,n):
  if a[i-1]>a[i]:
    ans=ans+a[i-1]-a[i]
    a[i]=a[i-1]
print(ans)

Solution (Python):


N = int(input())
A = list(map(int,input().split()))


ans = 0
now_max = A[0]

for i in range(1, N):
    
    if(now_max < A[i]):
        now_max = A[i]
    else:
        ans += now_max - A[i]

print(ans)

Solution (Python):
import sys, math
from collections import defaultdict, deque, Counter
from bisect import bisect_left, bisect_right
from itertools import combinations, permutations, product
from heapq import heappush, heappop
from functools import lru_cache
input = sys.stdin.readline
rs = lambda: input().strip()
ri = lambda: int(input())
rl = lambda: list(map(int, input().split()))
mod = 1000000007
sys.setrecursionlimit(1000000)

N = ri()
A = rl()

s = 0
prev = A[0]
for i in range(1, N):
	if A[i] < prev:
		dif = prev-A[i]
		A[i] += dif
		s += dif
	prev = A[i]
print(s)

Solution (Python):
n = int(input())
a = list(map(int, input().split()))
ans = 0
for i in range(1, n):
    ans += max(a[i-1] - a[i], 0)
    a[i] = max(a[i-1], a[i])
print(ans)

Solution (Python):
n = int(input())
a = list(map(int, input().split()))
ans = 0
high = a[0]
for i in range(1, n):
    if a[i] < high:
        ans += high - a[i]
    else:
        high = a[i]
print(ans)

Solution (Python):
INT = lambda: int(input())
INTM = lambda: map(int,input().split())
STRM = lambda: map(str,input().split())
STR = lambda: str(input())
LIST = lambda: list(map(int,input().split()))
LISTS = lambda: list(map(str,input().split()))
def do():
    n=INT()
    A=LIST()
    ans=0
    mina=0
    for a in A:
        mina=max(mina,a)
        ans+=max(0,mina-a)
    
    print(ans)
    
if __name__ == '__main__':
    do()

Solution (Python):
n = int(input())
a = list(map(int, input().split()))

step = 0
for i in range(1, n):
    if a[i-1] > a[i]:
        step += a[i-1]-a[i]
        a[i] = a[i-1]
print(step)

Solution (Python):
n = int(input())
a = list(map(int, input().split()))

ans = 0
m = a[0]
for i in range(n):
    if a[i] < m:
        ans += m-a[i]
    else:
        m = a[i]
print(ans)

Solution (Python):
n = int(input())
a = list(map(int, input().split()))
ans = 0
cur = a[0]
for i in range(1, n):
    if cur <= a[i]:
        cur = a[i]
    else:
        ans += cur - a[i]
        a[i] = cur
        cur = a[i]
print(ans)

Solution (Python):
n=int(input())
a=list(map(int,input().split()))

ans=0
for i in range(1,n):
    if a[i-1]<=a[i]:
        continue
    x=a[i-1]-a[i]
    ans+=x
    a[i]+=x
print(ans)

Solution (Python):
n = int(input())
li = list(map(int, input().split()))

check = 0
ans = 0
for i in range(n):
    if i == 0:
        check = li[0]
        continue
    
    if check >= li[i]:
        ans += check - li[i]
    else:
        check = li[i]
        
print(ans)

Solution (Python):
n=int(input())
a=list(map(int, input().split()))

ans=0
for i in range(1,n):
    if a[i]<a[i-1]:
        ans+=a[i-1]-a[i]
        a[i]=a[i-1]
print(ans)

Solution (Python):
N = int(input())
A = list(map(int,input().split()))

prev = 0
ans = 0
for a in A:
  if a >= prev:
    prev = a
  else:
    ans += prev-a


print(ans)

Solution (Python):
n = int(input())
a = list(map(int, input().split()))
cnt = 0
before = a[0]

for i in range(n):
    if before > a[i]:
        cnt += before - a[i]
    else:
        before = a[i]

print(cnt)

Solution (Python):
def main():
    n = int(input())
    inlis = list(map(int, input().split()))

    tmp = inlis[0]
    ans = 0

    for i in range(1, n):
        if inlis[i] < tmp:
            ans += tmp - inlis[i]
        else:
            tmp = inlis[i]
    print(ans)


if __name__ == "__main__":
    main()

Solution (Python):

import sys
input = sys.stdin.readline
N = int(input())
A = list(map(int,input().split()))

ans = 0
h = 0
for a in A:
	if h > a:
		ans += h - a
	else:
		h = a
print(ans)

Solution (Python):


import sys
iim = lambda: map(int, sys.stdin.readline().rstrip().split())

def resolve():
    it = map(int, sys.stdin.read().split())
    N = next(it)
    A = list(it)

    ans = 0
    x = A[0]

    for i in range(1, N):
        ai = A[i]
        diff = x - ai
        if diff >= 0:
            ans += diff
        else:
            x = ai

    print(ans)

if __name__ == "__main__":
    resolve()

Solution (Python):
n = int(input())
a = list(map(int, input().split()))

ans = 0
for i in range(1, n):
    if a[i-1] > a[i]:
        ans += a[i-1] - a[i]
        a[i] = a[i-1]

print(ans)

Solution (Python):
from sys import stdin, setrecursionlimit

setrecursionlimit(10 ** 7)

from heapq import heappush, heappop
from bisect import bisect_left, bisect_right
from collections import deque, defaultdict, Counter
from itertools import combinations, permutations, combinations_with_replacement
from itertools import accumulate
from math import ceil, sqrt, pi, radians, sin, cos

MOD = 10 ** 9 + 7
INF = 10 ** 18

N = int(input())

A = list(map(int, input().split()))





if N == 1:
    print(0)
    exit()
    
answer = 0
max_a = A[0]

for a in A[1:]:
    max_a = max(max_a, a)
    answer += max_a - a

print(answer)

Solution (Python):
n = int(input())
A = list(map(int,input().split()))
if n ==1: print(0);exit()
cnt = 0
for i in range(1,n):
    if A[i]<A[i-1]:
        cnt += A[i-1]-A[i]
        A[i] = A[i-1]
        
print(cnt)

Solution (Python):
from sys import stdin


def main():
    _in = [_.rstrip() for _ in stdin.readlines()]
    N = int(_in[0])  
    A_arr = list(map(int, _in[1].split(' ')))  
    
    cnt = A_arr[0]
    ans = 0
    for A in A_arr:
        if A < cnt:
            ans += (cnt - A)
        else:
            cnt = A
    
    print(ans)


if __name__ == "__main__":
    main()

Solution (Python):
ma = lambda :map(int,input().split())
lma = lambda :list(map(int,input().split()))
tma = lambda :tuple(map(int,input().split()))
ni = lambda:int(input())
yn = lambda fl:print("Yes") if fl else print("No")
import collections
import math
import itertools
import heapq as hq
n = ni()
A = lma()
prev=0
ans=0
for a in A:
    if a<prev:
        ans+=(prev-a)
    prev=max(a,prev)
print(ans)

Solution (Python):
N = int(input())
A = list(map(int, input().split()))
count = 0
max_height = A[0]

for i in range(N):
    if A[i] > max_height:
        max_height = A[i]
    elif A[i] == max_height:
        continue
    else:
        count += max_height - A[i]

print(count)

Solution (Python):
n = int(input())
a = list(map(int,input().split()))
last = -1
ans = 0
for i in range(n):
  if a[i] >= last:
    last = a[i]
  else:
    ans += last - a[i]
  
print(ans)

Solution (Python):
N = int(input())
A = list(map(int, input().split()))
tmp = A[0]
ans = 0
for i in range(1, N):
    if tmp > A[i]:
        ans += tmp - A[i]
    else:
        tmp = A[i]
print(ans)

Solution (Python):


import sys
import pprint

sys.setrecursionlimit(10 ** 6)

class Logger:
	def __init__(self, debug):
		self.debug = debug
	def print(self, *args):
		if self.debug:
			pprint.pprint(args)


def main():
	log = Logger(0)
	n = int(sys.stdin.readline())
	a = list(map(int, sys.stdin.readline().split()))
	ans = 0
	for i in range(1, n):
		if a[i-1] > a[i]:
			ans += a[i-1] - a[i]
			a[i] = a[i-1]
	log.print(a)
	print(ans)

main()

Solution (Python):
def main(sample_file = ''):

    """ convenient functions
    
    
    
    
    
    """

    """convenient decorator
    
    
        
        
        
        
        
        
        
        
        
        
    """
    
    
    import sys
    sys.setrecursionlimit(10**7)
    from itertools import accumulate, combinations, permutations, product 
    
    from math import factorial, ceil, floor, sqrt
    def factorize(n):
        """return the factors of the Arg and count of each factor
        
        Args:
            n (long): number to be resolved into factors
        
        Returns:
            list of tuples: factorize(220) returns [(2, 2), (5, 1), (11, 1)]
        """
        fct = []  
        b, e = 2, 0  
        while b * b <= n:
            while n % b == 0:
                n = n // b
                e = e + 1
            if e > 0:
                fct.append((b, e))
            b, e = b + 1, 0
        if n > 1:
            fct.append((n, 1))
        return fct
    def combinations_count(n, r):   
        """Return the number of selecting r pieces of items from n kinds of items.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        
        if n < 0 or r < 0:
            raise Exception('combinations_count(n, r) not defined when n or r is negative')
        if n - r < r: r = n - r
        if r < 0: return 0
        if r == 0: return 1
        if r == 1: return n
        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]
        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot
        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
        return result
    def combinations_with_replacement_count(n, r):
        """Return the number of selecting r pieces of items from n kinds of items allowing individual elements to be repeated more than once.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        if n < 0 or r < 0:
            raise Exception('combinations_with_replacement_count(n, r) not defined when n or r is negative')
        elif n == 0:
            return 1
        else:
            return combinations_count(n + r - 1, r)
    from bisect import bisect_left, bisect_right
    from collections import deque, Counter, defaultdict 
    from heapq import heapify, heappop, heappush, heappushpop, heapreplace,nlargest,nsmallest 
    from copy import deepcopy, copy 
    import operator
    from operator import itemgetter 
    
    
    from functools import reduce, lru_cache
    def chmin(x, y):
        """change minimum
        if x > y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current minimum value
            y (long): potential minimum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x > y:
            x = y
            return (x, True)
        else:
            return (x, False)
    def chmax(x, y):
        """change maximum
        if x < y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current maximum value
            y (long): potential maximum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x < y:
            x = y
            return (x, True)
        else:
            return (x, False)

    from fractions import gcd 
    def gcds(numbers):
        return reduce(gcd, numbers)
    def lcm(x, y):
        return (x * y) // gcd(x, y)
    def lcms(numbers):
        return reduce(lcm, numbers, 1)
    def make_divisors(n, reversed=False):
        """create list of divisors
        
        Args:
            number (int): number from which list of divisors is created
            reversed (bool, optional): ascending order if False. Defaults to False.
        
        Returns:
            list: list of divisors
        """
        divisors = set()
        for i in range(1, int(n**0.5)+1):
            if n % i == 0:
                divisors.add(i)
                divisors.add(n//i)
        return sorted(list(divisors),reverse=reversed)
    
    
    
    INF = 10 ** 18
    MOD = 10 ** 9 + 7
    AtoZ = list('abcdefghijklmnopqrsruvwxyz') 
    modpow = lambda a, n, p = MOD: pow(a, n, p) 
    def modinv(a, p = MOD):
        
        
        return modpow(a, p-2, p)
    def modinv_list(n, p = MOD):
        if n <= 1:
            return [0,1][:n+1]
        else:
            inv_t = [0,1]
            for i in range(2, n+1):
                inv_t += [inv_t[p % i] * (p - int(p / i)) % p]
            return inv_t
    def modfactorial_list(n, p = MOD):
        if n == 0:
            return [1]
        else:
            l = [0] * (n+1)
            tmp = 1
            for i in range(1, n+1):
                tmp = tmp * i % p
                l[i] = tmp
            return l
    def modcomb(n, k, fac_list = [], p = MOD):
        
        
        from math import factorial
        if n < 0 or k < 0 or n < k: return 0
        if n == 0 or k == 0: return 1
        if len(fac_list) <= n:
            a = factorial(n) % p
            b = factorial(k) % p
            c = factorial(n-k) % p
        else:
            a = fac_list[n]
            b = fac_list[k]
            c = fac_list[n-k]
        return (a * modpow(b, p-2, p) * modpow(c, p-2, p)) % p
    def modadd(a, b, p = MOD):
        return (a + b) % MOD
    def modsub(a, b, p = MOD):
        return (a - b) % p
    def modmul(a, b, p = MOD):
        return ((a % p) * (b % p)) % p
    def moddiv(a, b, p = MOD):
        return modmul(a, modpow(b, p-2, p))

    class UnionFindTree:
        """union find tree class
        TODO: fix this description...
        how to use (example):
        >>  uf = UnionFindTree(N) 
        >>  if uf.find_root(a) == uf.find_root(b):
        >>      do something
        >>  else:
        >>      do something
        >>      uf.unite(a, b)
        """
        def __init__(self, N):
            self.root = [-1] * (N+1)
            self.rank   = [0]  * (N+1)
            self.connected_num = [1] * (N+1)
    
        def find_root(self,x):
            root = self.root
            while root[x] != -1:
                x = root[x]
            return x
    
        def unite(self,x,y):
            root = self.root
            rank = self.rank
            connected_num = self.connected_num
            find_root = self.find_root
    
            rx = find_root(x)
            ry = find_root(y)
            if rx != ry:
                if rank[rx] < rank[ry]:
                    root[rx] = ry
                    rx,ry = ry,rx
                else:
                    if rank[rx] == rank[ry]:
                        rank[rx] += 1
                    root[ry] = rx       
                connected_num[rx] += connected_num[ry]

    class SegTree:
        """
        ref: https://qiita.com/takayg1/items/c811bd07c21923d7ec69
        init(init_val, ide_ele): 配列init_valで初期化 O(N)
        update(k, x): k番目の値をxに更新 O(logN)
        query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)
        """
        def __init__(self, init_val, segfunc, ide_ele):
            """
            init_val: 配列の初期値
            segfunc: 区間にしたい操作
            ide_ele: 単位元
            n: 要素数
            num: n以上の最小の2のべき乗
            tree: セグメント木(1-index)
            """
            n = len(init_val)
            self.segfunc = segfunc
            self.ide_ele = ide_ele
            self.num = 1 << (n - 1).bit_length()
            self.tree = [ide_ele] * 2 * self.num
            
            for i in range(n):
                self.tree[self.num + i] = init_val[i]
            
            for i in range(self.num - 1, 0, -1):
                self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])

        def update(self, k, x):
            """
            k番目の値をxに更新
            k: index(0-index)
            x: update value
            """
            k += self.num
            self.tree[k] = x
            while k > 1:
                self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])
                k >>= 1

        def query(self, l, r):
            """
            [l, r)のsegfuncしたものを得る
            l: index(0-index)
            r: index(0-index)
            """
            res = self.ide_ele
            l += self.num
            r += self.num
            while l < r:
                if l & 1:
                    res = self.segfunc(res, self.tree[l])
                    l += 1
                if r & 1:
                    res = self.segfunc(res, self.tree[r - 1])
                l >>= 1
                r >>= 1
            return res

    
    
    
    
    
    
    
    

    def BellmanFord(N, M, ABC, vertex_start, vertex_end, value_if_inf = -1, find_shortest = False):
        """to calculate furthest or shortest length between vertex_start and vertex_end using BellmanFord algorithm
        
        Args:
            N (int): number of vertices
            M (int): number of edges
            ABC (list): [(ai, bi, ci) for _ in range(N)] where i-th edge is directed from vertex ai to vertex bi and the length is ci 
            vertex_start (int): start vertex. usually use 0.
            vertex_end (int): end vertex. usually use N-1.
            value_if_inf (int or string as you like, optional): value you want when the furthest (or shortest) distance is infinite (or -infinite). Defaults to -1.
            find_shortest (bool, optional): choose False to find furthest path. Defaults to False.
        
        Returns:
            int or string: normally int (but can be str if you set value_if_inf to str)
            
        Example:
                N, M, P = R()
                ABC = [R() for _ in range(M)]
                ABC = [(a-1, b-1, c-P) for a, b, c in ABC]
                print(BellmanFord(N, M, ABC, 0, N-1, value_if_inf = 'inf'))

        """

        def make_reachable_list(N, M, ABC, vertex_start, vertex_end):
            reachable_to_direct = defaultdict(list)
            reachable_from_direct = defaultdict(list)
            reachable_from_start = [False] * N
            reachable_to_end = [False] * N
            reachable_from_start[vertex_start] = True
            reachable_to_end[vertex_end] = True
            reachable_from_both_sides = [False] * N
            dfs_from_start = []
            dfs_to_end = []
            for a, b, c in ABC:
                reachable_to_direct[a].append(b)
                reachable_from_direct[b].append(a)
                if a == vertex_start:
                    dfs_from_start.append(b)
                    reachable_from_start[b] = True
                if b == vertex_end:
                    dfs_to_end.append(a)
                    reachable_to_end[a] = True
            while dfs_from_start:
                v = dfs_from_start.pop()
                for i in reachable_to_direct[v]:
                    if not reachable_from_start[i]:
                        reachable_from_start[i] = True
                        dfs_from_start.append(i)
            while dfs_to_end:
                v = dfs_to_end.pop()
                for i in reachable_from_direct[v]:
                    if not reachable_to_end[i]:
                        reachable_to_end[i] = True
                        dfs_to_end.append(i)
            for i in range(N):
                reachable_from_both_sides[i] = reachable_from_start[i] and reachable_to_end[i]
            return reachable_from_both_sides
        
        reachable_from_both_sides = make_reachable_list(N, M, ABC, vertex_start, vertex_end)
        
        if find_shortest:
            dist = [INF for i in range(N)]
        else:
            dist = [-INF for i in range(N)]
        
        dist[vertex_start] = 0
        for i in range(N):
            updated = False
            for a, b, c in ABC:
                if not reachable_from_both_sides[a]:
                    continue
                elif find_shortest:
                    update_condition = dist[a] + c < dist[b]
                else:
                    update_condition = dist[a] + c > dist[b]
                if dist[a] != INF and update_condition:
                    dist[b] = dist[a] + c
                    updated = True
                    if i == N-1:
                        return value_if_inf
            if not updated:
                break
        return dist[vertex_end]

    
    def warshall_floyd(number_vertex, XYD, shift_one_for_vertex=False):
        
        
        
        
        
        d = [[float("inf")]*number_vertex for i in range(number_vertex)]
        for x, y, dist in XYD:
            if shift_one_for_vertex:
                x = x - 1
                y = y - 1
            d[x][y] = dist
            d[y][x] = dist
        for i in range(number_vertex):
            d[i][i] = 0 
        for k in range(number_vertex):
            for i in range(number_vertex):
                for j in range(number_vertex):
                    d[i][j] = min(d[i][j],d[i][k] + d[k][j])
        return d


    """ initialize variables and set inputs
    
        
        
            
            
    
        
        
        
        
        
        
        
    
        
        
        
        
    
        
        
    """

    
    r = lambda: sys.stdin.readline().strip()
    r_int = lambda: int(r())
    r_float = lambda: float(r())
    R = lambda: list(map(int, r().split()))
    R_str = lambda: r().split()
    R_map = lambda: map(int, r().split())
    R_float = lambda: list(map(float, r().split()))
    R_tuple = lambda: tuple(map(int, r().split()))

    """ how to treat input
    
    
    
    
    
    
    
    """

    
    if sample_file:
        sys.stdin = open(sample_file)
        
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    N = r_int()
    A = R()
    
    tmp_max = A[0]
    ans = 0
    for a in A:
        if a < tmp_max:
            ans += tmp_max - a
        else:
            tmp_max = a
    print(ans)

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    


    
    
    

    """memo: how to use defaultdict of list
    
    Dic = defaultdict(list)
    
    Dic[x].append(y)
    
    for k, v in Dic.items():
    """
    
    """memo: how to solve binary problems
    
    >>> a = 5
    >>> bin_str_a = format(a, '
    >>> print(bin_str_a)
    0b0101 
    """
    
    """memo: how to solve the problem
    creating simple test/answer
    greed
    simple dp
    graph
    """

if __name__ == '__main__':
    main()

Solution (Python):
N = int(input())
a = list(map(int,input().split()))
step = 0
M = a[0]
for i in range(1,N):
    if a[i] <= M:
        step += M-a[i]
    else:
        M = a[i]

print(step)

Solution (Python):
def main():
    import sys
    N=int(sys.stdin.readline())
    A=list(map(int,sys.stdin.readline().split()))
    mx=0
    h=0
    for a in A:
        if a<mx:
            h+=mx-a
        else:
            mx=a
    print(h)

main()

Solution (Python):



def ri():
    return int(input())

def rl():
    return list(input().split())

def rli():
    return list(map(int, input().split()))

def main():
    n = ri()
    la = rli()
    h = 0
    ans = 0
    for a in la:
        if a < h:
            ans += h-a
        else:
            h = a
    print(ans)


if __name__ == '__main__':
    main()

Solution (Python):
n = int(input())
A = list(map(int,input().split()))
pre = A[0]
ans = 0
for a in A:
    if pre > a:
        ans += pre - a
        pre = pre
    else:
        pre = a

print(ans)

Solution (Python):
N = int(input())
As = list(map(int, input().split()))

b = As[0]
rlt = 0

for i in range(1,N):
  if b > As[i]:
    rlt += b-As[i]
  else:
    b = As[i]
    
print(rlt)

Solution (Python):
n = int(input())
lis = list(map(int,input().split()))

t = lis[0]
ans = 0
for i in range(1, n):
    if lis[i] < t:
        ans += t-lis[i]
    else:
        t = lis[i]

print(ans)

Solution (Python):
n=int(input())
a=list(map(int, input().split()))
curr=a[0]
ans=0
for i in range(n):
    if a[i]<curr:
        ans+=(curr-a[i])
    else:
        curr=max(curr, a[i])
print(ans)

Solution (Python):
n = int(input())
arr = list(map(int, input().split()))

MAX = arr[0]

ans = 0
for x in arr:
    ans += max(MAX - x, 0)
    MAX = max(MAX, x)

print(ans)

Solution (Python):
n = int(input())
a = list(map(int,input().split()))

ans = 0
for i in range(1,n):
    if a[i] < a[i-1]:
        ans += a[i-1]-a[i]
        a[i] = a[i-1]
print(ans)

Solution (Python):
N = int(input())
A = list(map(int,input().split()))
now = 0
ans = 0
for i in A:
  if now > i:
    ans += now - i
  else:
    now = i
print(ans)

Solution (Python):
N = int(input())
A = list(map(int, input().split()))
a0 = A[0]
res = 0
for a in A[1:]:
    if a < a0:
        res += a0-a
    else:
        a0 = a
print(res)

Solution (Python):
n = int(input())
a = list(map(int,input().split()))

count = 0
high = a[0]

for i in range(1, n):
  if a[i] >= high:
    high = a[i]
    
  else:
    count += high - a[i]
    
print(count)

Solution (Python):
n=int(input())
a=list(map(int,input().split()))

s=0
for i in range(1,n):
  if a[i-1]>a[i]:
    s+=a[i-1]-a[i]
    a[i]=a[i-1]
print(s)

Solution (Python):

n, *a = map(int, open(0).read().split())
p = 0
ans = 0
for i in a:
    ans += max(p - i, 0)
    p = max(p, i)
print(ans)

Solution (Python):
N = int(input())
A = list(map(int,input().split()))
ans = 0
for i in range(1,N):
    if A[i-1] > A[i]:
        ans += abs(A[i-1]-A[i])
        A[i] = A[i-1]
    else:
        continue
print(ans)

Solution (Python):
N = int(input())
A = list(map(int, input().split()))

ans = 0
cur = A[0]
for i in range(1, N):
    if A[i] < cur:
        ans += cur - A[i]
    else:
        cur = A[i]
print(ans)

Solution (Python):
N = input()
A = list(map(int, input().split()))
now = A[0]
sum = 0
for a in A[1:]:
    if now <= a:
        now = a
    else:
        sum += now - a
print(sum)

Solution (Python):
import sys
import heapq, functools, collections
import math, random
from collections import Counter, defaultdict






def solve(lst):  
    console("----- solving ------")

    curmax = 0
    res = 0
    for x in lst:
        res += max(curmax - x, 0)
        curmax = max(curmax, x)

    
    return res


def console(*args):  
    print('\033[36m', *args, '\033[0m', file=sys.stderr)
    return




for case_num in [1]:
    
    

    
    _ = int(input())
    
    
    

    
    lst = list(map(int,input().split()))

    
    
    
    
    
    

    res = solve(lst)  
    
    
    

    
    print(res)

Solution (Python):
n = int(input())
a = list(map(int,input().split()))

ans = 0
for i in range(1,n):
    if a[i-1] > a[i]:
        ans += a[i-1] - a[i]
        a[i] = a[i-1]
print(ans)