#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <vector>
#include <map>
#include <queue>

#define LL long long
#define ULL unsigned long long
#define PB push_back

using namespace std;

int main(void){

    ifstream in("operatii.in");
    ofstream out("operatii.out");
    
    int N,K,i,l;
    
    in >> N;
    
    l = 0;
    LL sol = 0;
    
    for (int i=0;i<N;i++){
        in >> K;
        if (K>l) sol += K-l;
        l = K;
    }
    
    out << sol;
    
    in.close();
    out.close();

return 0;
}