#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define maxn 200005
#define maxm 10000005
ll mapping[2*maxm];
ll a[maxn];
map<ll,ll> dau;
vector<ll> z;
ll n;
ll f[7]={1,11,111,1111,11111,111111,1111111};
void init(){
    for(ll i=1;i<=9;i++){
       for(ll j=0;j<7;j++) z.push_back(i*f[j]);
   }
}
int main(){
    // freopen("lala.out","w",stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
   init();
    cin>>n;
    ll x;
    for(ll i=0;i<n;i++){
        cin>>x;
        a[i]=x;
        mapping[x]++;
    }
    ll ans=0;
    for (ll u=0;u<63;u++){
           ll summa = z[u];
        for(ll i=0;i<n;i++){
            if(summa-a[i]<0) continue;
            ans = ans + mapping[summa-a[i]];
            if(summa-a[i]==a[i]) ans--;
        }
    }
    ans/=2;
    cout<<ans;
    
   return 0;
}