#include<fstream.h>
int main(){
long nr,n,v[1000000],max,i;
ifstream f("operatii.in");
ofstream g("operatii.out");
f>>n;
max=0;   nr=0;
for(i=1;i<=n;i++){f>>v[i];
if(v[i]>max) nr=nr+v[i]-max;
max=v[i];}

g<<nr;
}