#include<fstream>
#define maxn 1000005

using namespace std;

ifstream f("operatii.in");
ofstream g("operatii.out");

long long n,a[maxn],k,i;

int main()
{
    f>>n;

    for(i=1;i<=n;++i)
    {
        f>>a[i];
        if(a[i]>a[i-1])
            k+=a[i]-a[i-1];
    }

    g<<k<<"\n";

    f.close();
    g.close();

    return 0;
}