#include<cstdio>
#include<cstdlib>
#include<cstring>
#define N 100005
#define ri register int
#define fo(i,l,r) for(ri i=l;i<=r;i++)
#define rf(i,r,l) for(ri i=r;i>=l;i--)
#define ll long long
using namespace std;
int n,a[N],ans;
void swap(int &x,int &y){int t=x;x=y;y=t;}
int max(int x,int y){return x>y?x:y;}
int min(int x,int y){return x<y?x:y;}
int read(){
	int sum=0;bool f=0;char c=getchar();
	for(;c<48||c>57;c=getchar())if(c==45)f=1;
	for(;c>=48&&c<=57;c=getchar())sum=sum*10+(c&15);
	return f?-sum:sum;
}
int main(){
	freopen("2018road.in","r",stdin);freopen("2018road.out","w",stdout);
	n=read();fo(i,1,n)a[i]=read();
	for(ri i=1,sum=0;i<=n;sum=a[i++])
		if(a[i]>sum)
			ans+=a[i]-sum;
	printf("%d",ans);
	return 0;
}