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