#include <iostream>
#include <fstream>

using namespace std;

ifstream fin ("operatii.in");
ofstream fout ("operatii.out");

long long i,a[200001],s=0,op,n;
int main()
{
fin>>n;
for(i=1;i<=n;i++) fin>>a[i];
for(i=0;i<=n;i++)
{op=a[i+1]-a[i];
if(op>0) s=s+op;}
fout<<s;


return 0;

}