#include<stdio.h>
long n,i,a[1000001];
long long rez=0;
int main()
{
freopen("operatii.in","r",stdin);
freopen("operatii.out","w",stdout);
scanf("%ld",&n);
for(i=1;i<=n;i++)
{
scanf("%ld",&a[i]);
if(a[i-1]<a[i])
rez=rez+(a[i]-a[i-1]);
}
printf("%lld",&rez);
return 0;
}