#include<fstream>
#define DM 1000007
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");

int N,x;
int G[DM];
long long Sol;

int main()
{
    fin>>N;

    for(int i=1;i<=N;++i)
    {
        fin>>G[i];
        if(G[i]>x)  Sol+=G[i]-x;
        x=G[i];
    }

    fout<<Sol<<"\n";

    fin.close();
    fout.close();
    return 0;
}