# include <stdio.h>

# define input "operatii.in"
# define output "operatii.out"

# define max 1000001
# define maxim(a,b) (a>b?a:b)

long long a[max];
long long i,n;
long long res;

int main()
{
    freopen( input, "r", stdin );
    freopen( output, "w", stdout );
    
    scanf("%lld", &n);    
    for(i=1;i<=n;i++)
    {
       scanf("%lld",&a[i]);
       if(a[i] > a[i-1])
          res+=a[i]-a[i-1];
    }

    
    printf("%lld",res);
    
    return 0;
}
/*
   1. #include<fstream.h>  
   2. unsigned long i,n,s=0, v[1000001],j;  
   3. int main()  
   4. {  
   5. ifstream f("operatii.in");  
   6. ofstream g("operatii.out");  
   7. f>>n;  
   8. for(i=1;i<=n;i++)  
   9.   f>>v[i];  
  10. for(i=1;i<=n;i++)  
  11.  if(v[i]>v[i-1]) {j=v[i]-v[i-1];s+=j;}  
  12.   
  13. g<<s;  
  14. f.close();  
  15. g.close();  
  16. return 0;  
  17. }  

*/