#include <bits/stdc++.h>
#include <atcoder/all>
#include <boost/polygon/point_data.hpp>
#include <boost/polygon/voronoi.hpp>
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(x) begin(x),end(x)
#define sz(x) (int)(x).size()
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
using vll=vector<ll>;
using vvll=vector<vll>;
using pll=pair<ll,ll>;

// using mint=modint;

// using BoostPoint=boost::polygon::point_data<int>;
// using Voronoi=boost::polygon::voronoi_diagram<double>;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

    ll N;
    cin>>N;
    vll p;
    while(N>0){
        p.push_back(N%10);
        N/=10;
    }
    vll q=convolution_ll(p,p);
    ll m=sz(q);
    rep(i,0,m){
        if(q[i]<10)continue;
        ll carry=q[i]/10;
        q[i]%=10;
        if(i==m-1)q.push_back(carry);
        else q[i+1]+=carry;
    }
    while(q.back()>=10){
        ll carry=q.back()/10;
        q.back()%=10;
        q.push_back(carry);
    }
    rrep(i,0,sz(q))cout<<q[i];
    cout<<'\n';

}