#include <cstdio>

#define file_in "operatii.in"
#define file_out "operatii.out"

int N,v[1010000],i;
long long ans;

int main(){
	
	freopen(file_in,"r",stdin);
	freopen(file_out,"w",stdout);

	scanf("%d\n", &N);
	for (i=1;i<=N;++i)
		 scanf("%d", &v[i]);
	ans=0;
	for (i=1;i<=N;++i)
		 if (v[i]>v[i-1])
			 ans+=(v[i]-v[i-1]);
	printf("%lld\n", ans);

	return 0;
	
}