#include <bits/stdc++.h>
#define ll long long
using namespace std;
ifstream fin("operatii.in");
ofstream fout("operatii.out");
typedef int vect[1000001];
vect a;
ll sol[1000001];
int n,i;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)fin>>a[i];
    for(i=1;i<=n;i++)
        if(a[i]>a[i-1])sol[i]+=sol[i-1]+a[i]-a[i-1];
        else sol[i]+=sol[i-1];
    fout<<sol[n]<<"\n";
    return 0;
}