#include <stdio.h>
#define input "operatii.in"
#define output "operatii.out"
#define nmax 1000001
long v[nmax],n;
long long sol;
void citire()
{
 int i;
 freopen(input,"r",stdin);
 scanf("%ld",&n);
 for (i=1;i<=n;i++)
     scanf("%ld",&v[i]);
}
void solve()
{
 int i;
 sol=v[1];
 for (i=1;i<n;i++)
     if (v[i+1]>v[i])
	sol+=v[i+1]-v[i];
}
void afisare()
{
 freopen(output,"w",stdout);
 printf("%lld",sol);
}
int main()
{
 citire();
 solve();
 afisare();
 return 0;
}