#include<iostream.h>
#include<fstream.h>
ifstream f("operatii.in");
ofstream g("operatii.out");
int main()
{
long n;
f>>n;
int x,y,i,c=0;
x=0;i=0;
{
while(i<n)
{
f>>y;i++;
if(y>x) c+=y-x;
x=y;
}
}
g<<c;
f.close();
g.close();
return 0;
}