#include <bits/stdc++.h>
using namespace std;

int main()
{
    ifstream cin ("operatii.in");
    ofstream cout ("operatii.out");
    long long n,i,j;
    long long cnt=0;
    long long x,prev=0;
    cin>>n;
    for(i=1;i<=n;i++)
    {
        cin>>x;
        if(x>prev)
            cnt+=x-prev;
        prev=x;
    }
    cout<<cnt;
    return 0;
}