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