//operatii   
#include<fstream.h>   
long int n,nr;   
int main()   
{long int a=0,b;   
ifstream f("operatii.in");   
ofstream g("operatii.out");   
f>>n;   
while(!f.eof())   
//for(i=1;i<=n;i++)   
{f>>b;   
if(b>a) nr+=(b-a);   
a=b;   
}   
g<<nr<<'\n';   
f.close();   
g.close();   
return 0;   
}