#include<fstream.h>
unsigned long i,n,s=0, v[1000001],j;
int main()
{
ifstream f("operatii.in");
ofstream g("operatii.out");
f>>n;
for(i=1;i<=n;i++)
  f>>v[i];
for(i=1;i<=n;i++)
 if(v[i]>v[i-1]) {j=v[i]-v[i-1];s+=j;}

g<<s;
f.close();
g.close();
return 0;
}