#include <iostream>
using namespace std;

const int N = 1010;
int n, a[N], f[N];

int main()
{
    cin >> n;
    for ( int i = 1; i <= n; i ++ ) cin >> a[i];
    for ( int i = 1; i <= n; i ++ )
    {
        f[i] = 1;
        for ( int j = 1; j < n; j ++ )
            if ( a[j] < a[i] ) f[i] = max(f[i], f[j] + a[i]);
    }
    int res = 0;
    for ( int i = 1; i <= n; i ++ ) res = max(f[i], res);
    cout << res;
    return 0;
}