#include <fstream>

using namespace std;

int main()
{   ifstream cin("operatii.in");
    ofstream cout("operatii.out");
    long long n,ok=0,cnt=0,x;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>x;
        if(x>ok)
        {

            cnt+=x-ok;
        }
        ok=x;
    }
    cout<<cnt;
    return 0;
}