#include<fstream>
#include<algorithm>
#include<vector>
#include<stdlib.h>

using namespace std;

ifstream fin("operatii.in");
ofstream fout("operatii.out");

int main()
{
    int n, i, s=0, maxx=0;
    fin>>n;
    int *v=(int*)malloc(n+1);

    for(i=1; i<=n; i++){
        fin>>v[i];
        if(v[i]>maxx) s+=v[i]-maxx;
       maxx=v[i]; }
    fout<<s;
}