Language: C++

p#include <bits/stdc++.h>
typedef long long ll;
#define mod 1000000007
#define INF 1000000000
#define endl "\n"
#define all(s) s.begin(),s.end()
#define pb push_back
#define uno unordered_map
#define pi 3.1415926536
#define dig(a) fixed<<setprecision(a)
#define w(zz) int zz; cin>>zz; while(zz--)
#define foreach(var,i) for(auto i = var.begin();i!=var.end();i++)
#define fast() ios_base::sync_with_stdio(false); cin.tie(NULL);
ll power(ll a, ll n) {ll res = 1; while (n) {if (n % 2) {res *= a;} n >>= 1; a *= a;} return res;}
ll powerm(ll a, ll n, ll m) {ll res = 1; while (n) {if (n % 2) {res = (res * a) % m;} n >>= 1; a = (a * a) % m;} return res;}
using namespace std;
int main(){
	fast();
	int n;
	cin>>n;
	vector<int> a(n);
	for(int i=0;i<n;i++){
		cin>>a[i];
	}
	int s = 0;
	int x = a[0];
	for(int i=1;i<n;i++){
		if(a[i]<x){
			s+=(x-a[i]);
		}
		x = max(a[i],x);
	}
	cout<<s<<endl;
	return 0;
}

Compiler output:
a.cc:1:2: error: stray '#' in program
    1 | p#include <bits/stdc++.h>
      |  ^
a.cc:1:1: error: 'p' does not name a type
    1 | p#include <bits/stdc++.h>
      | ^
a.cc:14:1: error: 'll' does not name a type; did you mean 'all'?
   14 | ll power(ll a, ll n) {ll res = 1; while (n) {if (n % 2) {res *= a;} n >>= 1; a *= a;} return res;}
      | ^~
      | all
a.cc:15:1: error: 'll' does not name a type; did you mean 'all'?
   15 | ll powerm(ll a, ll n, ll m) {ll res = 1; while (n) {if (n % 2) {res = (res * a) % m;} n >>= 1; a = (a * a) % m;} return res;}
      | ^~
      | all
a.cc: In function 'int main()':
a.cc:13:16: error: 'ios_base' has not been declared
   13 | #define fast() ios_base::sync_with_stdio(false); cin.tie(NULL);
      |                ^~~~~~~~
a.cc:18:9: note: in expansion of macro 'fast'
   18 |         fast();
      |         ^~~~
a.cc:13:50: error: 'cin' was not declared in this scope
   13 | #define fast() ios_base::sync_with_stdio(false); cin.tie(NULL);
      |                                                  ^~~
a.cc:18:9: note: in expansion of macro 'fast'
   18 |         fast();
      |         ^~~~
a.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
  +++ |+#include <iostream>
    1 | p#include <bits/stdc++.h>
a.cc:13:58: error: 'NULL' was not declared in this scope
   13 | #define fast() ios_base::sync_with_stdio(false); cin.tie(NULL);
      |                                                          ^~~~
a.cc:18:9: note: in expansion of macro 'fast'
   18 |         fast();
      |         ^~~~
a.cc:1:1: note: 'NULL' is defined in header '<cstddef>'; this is probably fixable by adding '#include <cstddef>'
  +++ |+#include <cstddef>
    1 | p#include <bits/stdc++.h>
a.cc:21:9: error: 'vector' was not declared in this scope
   21 |         vector<int> a(n);
      |         ^~~~~~
a.cc:1:1: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
  +++ |+#include <vector>
    1 | p#include <bits/stdc++.h>
a.cc:21:16: error: expected primary-expression before 'int'
   21 |         vector<int> a(n);
      |                ^~~
a.cc:23:22: error: 'a' was not declared in this scope
   23 |                 cin>>a[i];
      |                      ^
a.cc:26:17: error: 'a' was not declared in this scope
   26 |         int x = a[0];
      |                 ^
a.cc:31:21: error: 'max' was not declared in this scope
   31 |                 x = max(a[i],x);
      |                     ^~~
a.cc:33:9: error: 'cout' was not declared in this scope
   33 |         cout<<s<<endl;
      |         ^~~~
a.cc:33:9: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'