#include<fstream>
#include<algorithm>
#include<vector>
#define dll long long
using namespace std;
 
long long n,v[1000005],a,b;
 
int main()
{
    ifstream f("operatii.in");
    ofstream g("operatii.out");
    f>>n;
    int dif,i;
    dll contor=0;
    for(i=1;i<=n;i++)
    {
        f>>a;
        if(a>b)
        {
            dif=a-b;
            contor=contor+dif;
        }
        b=a;
    }
    g<<contor;
    f.close();
    g.close();
    return 0;
}