#include <iostream>
using namespace std;
int a[1005];
int main (void)
{
    int n,max=0; cin >> n;
    for (int i=0; i<n; i++)
        cin >> a[i];
        
    for (int i=0; i<n; i++)
        {
             int br=0,j=i,prosli=-1,start=a[i];
             if (a[i]!=-1) 
                while (true)
                      if (a[j]>prosli) {j++; prosli=a[j-1];} else break;
             if (prosli-start>max) max=prosli-start;         
             
        }
    cout << max << endl;    
    //system ("pause");
    return 0;
}