#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<math.h>
#include<stdlib.h>
#include <functional>
using namespace std;
int a[2222222],n,ans;
int main()
{
cin>>n;
for(int i=1;i<=n;i++)
cin>>a[i];
for(int i=2;i<=n;i++)
if(a[i]>a[i-1])
ans+=a[i]-a[i-1];
cout<<ans+a[1]<<endl;
return 0;
}