#include <fstream>
#define ll long long
using namespace std;

const int nmax=1e6+5;

int v[nmax];

int main()
{
    ifstream cin("operatii.in");
    ofstream cout("operatii.out");
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>v[i];
    ll s=0;
    for(int i=1;i<=n;i++)
        s+=max(0LL,(long long)(v[i]-v[i-1]));
    cout<<s;
    return 0;
}