#include <stdio.h>
#define DIM 1000002

int a[DIM],i,n;
long long x;

int main(){

  FILE *f = fopen("operatii.in", "r");
  FILE *g = fopen("operatii.out", "w");

  fscanf(f,"%d",&n);

  for (i=1;i<=n;i++)
    fscanf(f,"%d",&a[i]);

  for (i=1;i<=n;i++)
    if (a[i]>a[i-1])
      x+=a[i]-a[i-1];

  fprintf(g,"%lld",x);


  fclose(f);
  fclose(g);

  return 0;
}