#include<stdio.h>
FILE *f=fopen("operatii.in","r"),
     *g=fopen("operatii.out","w");
long long i,op=0,n,a,b;
int main()
{ fscanf(f,"%lld",&n);
  a=0;
  for(i=1;i<=n;i++){ fscanf(f,"%lld",&b);
                     if(b>a) op+=(b-a);
                     a=b;
                   }
  fprintf(g,"%lld\n",op);
  fclose(f);
  fclose(g);
  return 0;
}