#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int n, ret;
int a[1010];
vector < int > v;

int diff( vector < int > &v ){
    
    reverse( v.begin(), v.end() );
    int s = v[0];
    int ret = 0;
    for( int i = 1; i < v.size(); ++i ){
         s -= v[i];
         ret += s;
         s = v[i];
         
    }
    
    return ret;   
}

int main ( void ){
    
    scanf( "%d", &n );
    
    for( int i = 0; i < n; ++i ) scanf( "%d", &a[i] );
    int p = a[0];
    v.push_back( p );
    for( int i = 1; i <= n; ++i ){
         if( a[i] > a[i-1] ) v.push_back( a[i] );
         else{
              ret = max( ret, diff( v ) );
              v.clear();
              v.push_back( a[i] );
         }
    }
    
    
    printf( "%d\n", ret );
    
              
    
    
    return 0;   
}