#include <stdio.h>  

int main()  
{  
    
  unsigned long long v,nr,v1,v2,i,n;  
   
  freopen("operatii.in","r",stdin);
  freopen("operatii.out","w",stdout);
  
  scanf("%lld",&n);  
  scanf("%lld",&v1);
  
  v = v1;  
 
  for(i = 2; i<=n; i++)  
  {  
     scanf("%lld",&v2);  
     if(v1<v2)  
     v += v2-v1;  
     v1 = v2;  
  }  
  printf("%lld",(nr+v));  
  fclose(stdin);fclose(stdout);  
 return 0;  
}