#include <bits/stdc++.h>

using namespace std;

#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC optimize("-Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-funroll-all-loops,-fpeel-loops,-funswitch-loops")

typedef long long ll;
typedef unsigned long long ull;
#define int ll
#define forn(i, x, n) for (int i = x; i <= n; i++)
#define forn(i, n) for (int i = 0; i < n; i++)
#define cin(fib, n) forn(i, n) cin >> fib[i]
#define cout(fib, n) forn(i, n) cout << fib[i] << ' '
#define FastIO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define all(fib) fib.begin(), fib.end()
#define alln(fib, n) fib, fib + n
#define rall(fib) fib.rbegin(), fib.rend()
#define yes cout << "YES"
#define no cout << "NO"
#define yn(b) (b ? yes : no)
#define pb push_back
#define nl cout << "\n"
#define minPQ priority_queue<int, vector<int>, greater<int>>
#define vi vector<int>
#define vs vector<string>
const int mod = 1000000007;
const int N = 100010;
const int oo = LONG_LONG_MAX;


void solve() {

    int n,k; cin>>n>>k;

    map<char,int>mp;

    string s; cin>>s;

    int mx=0;
    forn(i,n)
    {
        mp[s[i]]++;
        mx=max(mx,mp[s[i]]);
    }

    bool t1=1,t2=1;


    for(auto i : mp)
        if(i.second%k)
            t1=0;


    for(auto i : mp)
        if(i.second%k > i.second/k)
            t2=0,t1=0;


    if(t1)
    {
        cout<<1<<endl;

        forn(i,k)
        {
            for(auto i : mp)
            {
                forn(ii,i.second/k)
                    cout<<i.first;
            }
        }
    }
    else if(t2)
    {
        string ans="";
        cout<<2<<endl;
        for(auto i : mp)
        {
            forn(j , i.second%k)
                ans+=i.first;
        }

        string ans2=ans;

        for(auto i : mp)
        {
            forn(j , i.second/k - i.second%k)
                ans2+=i.first;
        }

        forn(i,k)
        cout<<ans2;
        cout<<ans;

    }
    else
        cout<<3;








}


    signed main()
{
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif

    FastIO;
    int t = 1;
    //cin>>t;

    while (t--)
    {
        solve();
        nl;
    }


    return 0;
}