#include<bits/stdc++.h>
#define int long long
using namespace std;

#define DIM 100000
char buff[DIM];
int poz=0;

void read(long long &nr) {
	nr=0;
	while (buff[poz]<'0' || buff[poz]>'9') 
		if (++poz == DIM) fread(buff,1,DIM,stdin),poz=0;
		
	while ('0'<=buff[poz] && buff[poz]<='9') {
		nr=nr*10+buff[poz]-'0';
		if (++poz == DIM) fread(buff,1,DIM,stdin),poz=0;
	}
}

int n,rs,pr,x;

int32_t main() {
	freopen("operatii.in", "r", stdin);
	freopen("operatii.out", "w", stdout);
	read(n);
	read(pr); rs=pr;
	for (int i=2; i<=n; i++) {
		read(x);
		rs+=max(0LL,x-pr); pr=x;
	}
	cout<<rs;
	
	return 0;
}