#include <fstream>

using namespace std;

int n,v[1000005];

inline void Read()
{
    ifstream fin("operatii.in");
    int i;
    fin>>n;
    for(i=1;i<=n;i++)
        fin>>v[i];
    fin.close();
}

inline void Solve()
{
    int i;
    long long cnt=0;
    for(i=1;i<=n;i++)
        if(v[i]>v[i-1])
            cnt=cnt+v[i]-v[i-1];
    ofstream fout ("operatii.out");
    fout<<cnt<<"\n";
    fout.close();
}

int main()
{
    Read();
    Solve();
    return 0;
}