#include <fstream.h>
int main(){
unsigned long long n,x,p,i,x2;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
fin>>n;
p=0;
x2=0;
for (i=1;i<=n;i++){
    fin>>x;
    if (x>x2) p=p+x-x2;
    x2=x;
    }
    fout<<p;
    fout.close();




return 0;
}