///#include <iostream>
#include <fstream>
using namespace std;
long long v[1000005];
int main()
{
    ifstream cin("operatii.in");
    ofstream cout("operatii.out");
    long long n,prev=0,rez=0;
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>v[i];
        if(v[i]>prev)
            rez+=v[i]-prev;
        prev=v[i];
    }
    cout<<rez;
    return 0;
}