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