#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,ans,a[100010];
signed main(){
	cin>>n;
	cin>>a[1];
	if(a[1]<0) a[1]=-a[1];
	for(int i=2;i<=n;i++){
		cin>>a[i];
		if(a[i]<0) a[i]=-a[i];
		if(a[i-1]<0) a[i-1]=-a[i-1];
		int s=__gcd(a[i],a[i-1]);
		ans+=s;
	}
	cout<<ans;
}