#include<iostream>
using namespace std;
const int N=100010;
int a;
int mc[N];
int main()
{
    cin>>a;
    for(int i=1;i<=a;i++)
    cin>>mc[i];
    for(int i=a+1;i>=0;i--)
    mc[i]-=mc[i-1];
    int ans=0;
    for(int i=1;i<=a+1;i++)
    {
        if(mc[i]>=0)
        ans+=mc[i];
    }
    cout<<ans<<endl;
    return 0;
}