#include<stdio.h>
int main(){
	freopen("operatii.in","r",stdin);
	freopen("operatii.out","w",stdout);
	int n,i,a,b,sum;
	scanf("%d",&n);
	scanf("%d",&a);
	sum=a;
	for(i=1;i<n;++i){
		scanf("%d",&b);
		if(b>a)
			sum+=b-a;
		a=b;
	}
	
	printf("%d\n",sum);
	fclose(stdin);
	fclose(stdout);
	return 0;
}