#include<fstream>
using namespace std;
int n, i;
long long sum;
int v[1000005];
ifstream fin("operatii.in");
ofstream fout("operatii.out");
int main(){
    fin>> n;
    for(i = 1; i <= n; i++){
        fin>> v[i];
    }
    sum = v[1];
    for(i = 2; i <= n; i++){
        if(v[i] > v[i - 1]){
            sum += v[i] - v[i - 1];
        }
    }
    fout<< sum <<"\n";
    return 0;
}