PRIMES

#define task "PRIMES"
#include <iostream>
#include <cstdio>
#include <algorithm>

using namespace std;

using ll = long long;
using ld = long double;

constexpr int N = 6e6 + 5;
int n, k;

int f[N], prime[N], m;

void Read()
{
    cin >> n >> k;
}

void Solve()
{
    for (int i = 2; i < N; ++i)
    {
        if (!f[i])
            f[i] = prime[++m] = i;

        for (int j = 1; j <= m && prime[j] * i < N; ++j)
            f[prime[j] * i] = prime[j];
    }

    string ans;
    ans.reserve(600000);

    for (int i = 1; i <= n; ++i)
    {
        string p;

        for (int v = prime[i]; v; v /= 10)
            p.push_back(char(v % 10 + '0'));

        reverse(p.begin(), p.end());

        for (auto j : p)
        {
            while (k > 0 && !ans.empty() && j > ans.back())
            {
                ans.pop_back();
                --k;
            }
            ans.push_back(j);
        }
    }

    while (k--)
        ans.pop_back();

    cout << ans;
}

int32_t main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    if (fopen(task ".INP", "r"))
    {
        freopen(task ".INP", "r", stdin);
        freopen(task ".OUT", "w", stdout);
    }

    Read();
    Solve();
}