#include <bits/stdc++.h>

using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
int n,x,mx;
long long cnt;

int main()
{
    int i,x,last;
    fin>>n>>last;
    cnt = last;
    for(i=2;i<=n;i++)
    {
        fin>>x;
        if(x>last)
            cnt+=x-last;
        last = x;
    }
    fout<<cnt<<"\n";



    fout.close();
    return 0;
}