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