Debug

#include <bits/stdc++.h>

#define num 1000000007
#define formn(i,m,n) for(i=m;i<n;i++)
#define forn(i,n) for(i=0;i<n;i++)
#define fmno(i,m,n,o) for(i=m;i<n;i+=o)
#define ll long long

using namespace std;


int main() {
    long long i=0,j,k,n,t;
    cin>>t;
    while(t--)
    {
        cin>>n;
        k=0;
        vector<string> a(n);
        set<string> b;
        multiset<string> c;
        ll ini;
        forn(i,n)
        {
            cin>>a[i];
            c.insert(a[i]);
        }
        forn(ini,n)
        {
            i=b.size();
            b.insert(a[ini]);
            c.erase(c.find(a[ini]));
            char ch='0',p;
            for(int j=3;j>=0;j--)
            while(b.size()<=i)
            {
                p=a[ini][j];
                a[ini][j]= ch;
                if(c.find(a[ini])==c.end() && b.find(a[ini])==b.end())
                {
                    k++;
                    b.insert(a[ini]);
                    break;
                }
                a[ini][j]=p;
                ch = ch + 1;
                //cout<<ch;
            }
        }
        cout<<k<<'\n';
        forn(i,n)
        {
            cout<<a[i]<<" ";
        }
        cout<<'\n';

    }

    return 0;
}