//Vasilut
#include<fstream>
#define NN 1000001

using namespace std;
ofstream out("operatii.out");

int n,v[NN];
long long sol;

int main()
{
    ifstream in("operatii.in");
    in>>n;
    v[0]=0;
    for(int i=1;i<=n;i++)
    {
        in>>v[i];
        if( v[i] > v[i-1] )
            sol+=( v[i] - v[i-1] );
    }
    out<<sol<<'\n';
    return 0;
}