#include <fstream>
#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <string>
#include <math.h>

using namespace std;
#define ll long long
#define llu long long unsigned
#define pb push_back
#define mp make_pair

string problemName = "operatii";
string inFile = problemName+".in";
string outFile = problemName+".out";
ifstream fin(inFile.c_str());
ofstream fout(outFile.c_str());

int main(){
    int n,i,x,y;
    y = 0;
    llu sol = 0;
    fin>>n;
    for(i = 1;i <= n;i++){
        fin>>x;
        if(x > y){
            sol += x-y;
        }
        y = x;
    }
    fout<<sol;
    return 0;
}