#include<stdio.h>
#define lg 1000001
int a[lg],n,m,i;
long long nr;
int main()
{freopen("operatii.in","r",stdin);
 freopen("operatii.out","w",stdout);
 scanf("%d",&n);
 for(i=1;i<=n;i++) scanf("%d",&a[i]);
 for(i=1;i<=n;i++) if(a[i]!=a[i-1]) a[++m]=a[i];
 for(i=1;i<=m;i++)
  if(a[i]>a[i-1])nr=nr+a[i]-a[i-1];
 printf("%lld",nr);
 fclose(stdout);
 return 0;}