#include <bits/stdc++.h> //Andrei Alexandru a.k.a Sho10
#define ll long long
#define double long double
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define all(a) (a).begin(), (a).end()
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define pi pair
#define rc(s) return cout<<s,0
#define endl '\n'
#define mod 1000000007
#define PI 3.14159265359
#define MAXN 100005
#define INF 1000000005
#define LINF 1000000000000000005ll
#define CODE_START ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
ll n,a[200005],bit[200005];
void update(ll pos,ll val){
for(;pos<=n;pos+=pos&(-pos)){
bit[pos]+=val;
}
}
ll query(ll pos){
ll res=0;
for(;pos;pos-=pos&(-pos)){
res+=bit[pos];
}
return res;
}
vector<ll>g[200005];
int32_t main(){
CODE_START;
cin>>n;
for(ll i=1;i<=n;i++)
{
cin>>a[i];
g[a[i]].pb(i);
}
for(ll i=1;i<=n;i++)
{
update(i,1ll);
}
priority_queue<ll>q;
ll ans=0;
for(ll i=n;i>=1;i--){
for(auto it : g[i]){
q.push(it);
}
if(q.size()==0){
rc("-1");
}
ll x=q.top();
q.pop();
update(n-x+1,-1);
ans+=query(n-x+1);
}
cout<<ans<<endl;
}
