#include<stdio.h>
long a[1000001];
long long rez,n,i;
int main(void)
{
freopen("operatii.in","r",stdin);
freopen("operatii.out","w",stdout);
scanf("%lld",&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;
}