#include<stdio.h>  
  
long long a[1000000],n,i,k=0;  
  
int main()  
{  
 freopen("operatii.in","r",stdin);  
 freopen("operatii.out","w",stdout);  
   
 scanf("%lld",&n);  
   
 for(i=1;i<=n;i++)  
  {  
   scanf("%lld",&a[i]);  
   if(a[i]>a[i-1]) k=k+(a[i]-a[i-1]);  
     
  }  
printf("%lld",k);  
  
return 0;  
}