#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ar array
const int mxN=1e5, mxP=1e7; // change to 1e7
int n, nxt[mxP+1], ind[mxP+1], n2, p[mxN];
vector<ar<int, 2>> e[mxP];
int find(int i) {
return i^p[i]?p[i]=find(p[i]):i;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
cin >> n;
//n=100000;
for (int i=0; i<n; ++i) {
int x;
cin >> x;
//x=rng()%9999000+1000;
nxt[x]=x;
}
for (int i=1; i<=mxP; ++i)
if (nxt[i])
ind[i]=n2++;
for (int i=mxP-1; i; --i)
if (!nxt[i])
nxt[i]=nxt[i+1];
if (nxt[1]==1) {
cout << 0;
return 0;
}
for (int i=2; i<mxP; ++i) {
if (i^nxt[i])
continue;
if (nxt[i+1]<2*i&&nxt[i+1])
e[nxt[i+1]-i].push_back({ind[i], ind[nxt[i+1]]});
for (int j=2*i; j<=mxP&&nxt[j]; j+=i)
if (nxt[j]<j+i)
e[nxt[j]-j].push_back({ind[i], ind[nxt[j]]});
}
//sort(e.begin(), e.end());
iota(p, p+n2, 0);
int ans=0, cmp=n2;
for (int i=0; i<mxP; ++i)
for (ar<int, 2> a : e[i]) {
int u=find(a[0]), v=find(a[1]);
if (u^v) {
p[v]=u;
--cmp;
ans+=i;
}
}
assert(cmp==1);
cout << ans;
return 0;
}
