#include <fstream>
#include <vector>

using namespace std;

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

int main() {
    int n;
    fin>>n;
    vector<int>foo(n+1);
    long long ans=0;
    for(int i=1;i<=n;i++) {
        fin>>foo[i];
        if(foo[i]>foo[i-1]) {
            ans+=foo[i]-foo[i-1];
        }
    }
    fout<<ans<<"\n";
    return 0;
}
/**

**/