Go: package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"sort"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		n, p := io.NextInt(), io.NextInt()
		if n == -1 {
			break
		}
		isPrime := SieveOpt(200000)
		prime := make([]int, p)
		cnt := 0
		if n < 2 {
			prime[0] = 2
			cnt++
		}
		for i := (n + 1) / 2; i < len(isPrime) && cnt < p; i++ {
			if isPrime[i] == true {
				prime[cnt] = 2*i + 1
				cnt++
			}
		}
		comb := make([]int, 0, p*p)
		for i := 0; i < p; i++ {
			for j := i; j < p; j++ {
				comb = append(comb, prime[i]+prime[j])
			}
		}
		sort.Ints(comb)
		io.Println(comb[p-1])
	}
}

func SieveOpt(x int) []bool {
	flags := make([]bool, x/2) // flags[i] := 2*j+1 is prime
	for i := 1; i < x/2; i++ {
		flags[i] = true
	}
	sqrtXi := int(math.Ceil(math.Sqrt(float64(x)))) / 2
	for i := 1; i < sqrtXi; i ++ {
		if !flags[i] {
			continue
		}
		for j := 2 * i * (i + 1); j < x/2; j += 2*i + 1 {
			flags[j] = false
		}
	}
	return flags
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

int main(){
  int n,p;
  int prime[101000];

  for(int i=0;i<101000;i+=2)prime[i] = 0;
  for(int i=1;i<101000;i+=2)prime[i] = 1;
  prime[1] = 0;
  prime[2] = 1;

  int c = 3;
  while(c*c<101000){
    for(int i=3*c;i<101000;i+=2*c)prime[i] = 0;
    while(!prime[++c]);
  }

  while(1){
    cin >> n >> p;
    if(n<0 && p<0)break;

    vector<int> e;
    for(int i=0;i<p;i++){
      while(!prime[++n]);
      e.push_back(n);
    }

    vector<int> c;
    for(int i=0;i<(int)e.size();i++){
      for(int j=i;j<(int)e.size();j++){
	c.push_back(e[i] + e[j]);
      }
    }

    sort(c.begin(),c.end());
    cout << c[p-1] << endl;
  }
}

C++: #include <bits/stdc++.h>
using namespace std;

#define REP(i,s,n) for(int i=s;i<n;++i)
#define rep(i,n) REP(i,0,n)
#define SORT(c) sort((c).begin(),(c).end())
#define IINF INT_MAX
#define LLINF LLONG_MAX
 
typedef long long ll;
typedef pair<int, int> ii;

int main() {
	
	ll n, p;
	vector<int> prime;
	vector<bool> check(150000);
	
	check[1] = check[0] = true;
	REP(i, 2, 150000){
		if(!check[i]) prime.push_back(i);
		for(int j = 2; i * j < 150000; j++){
			check[i * j] = true;
		}
	}
	
	
	while(cin >> n >> p){
		if(n == -1 && p == -1) break;
		
		auto it = upper_bound(prime.begin(), prime.end(), n-1);
		vector<ll> tmp(2500);
		rep(i, 50){
			auto it2 = it;
			rep(j, 50){
				tmp[i*50+j] = (ll)(*it) + *it2;
				it2++;
			}
			it++;
		}
		
		SORT(tmp);
		//rep(i, 50) cout << tmp[i] << endl;
		
		//break;
		cout << tmp[p-1] << endl;
		
	}
	
	
	// your code goes here
	return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <algorithm>
#include <vector>
using namespace std;

bool isprime[200000];
int prime[100000];

void init() {
  fill(isprime, isprime+200000, true);
  isprime[0] = isprime[1] = false;
  int count = 0;
  for (int i=2; i<200000; i++) {
    if (isprime[i]) {
      prime[count] = i;
      // if (count < 10) // cerr << "prime[" << count << "] = " << prime[count] << endl;
      count++;
      for (int j=2; j<200000; j++) {
	if (i * j >= 200000) break;
	isprime[i*j] = false;
      }
    }
  }
}

int main() {
  init();
  int N, P;
  while (scanf("%d%d", &N, &P) != EOF && N != -1 && P != -1) {
    vector<int> V;
    int idx;
    for (idx=0; prime[idx]<=N; idx++) {
    }
    // cerr << "idx = " << idx << endl;
    // cerr << "prime[idx] = " << prime[idx] << endl;
    // cerr << "prime[0] = " << prime[0] << endl;
    for (int i=0; i<100; i++) {
      for (int j=0; j<=i; j++) {
	V.push_back(prime[idx+i] + prime[idx+j]);
	// // cerr << prime[idx+i] + prime[idx+j] << endl;
      }
    }
    sort(V.begin(), V.end());
    /*for (int p=0; p<100; p++) {
      // cerr << "V[" << p << "] = " << V[p] << endl;
      }*/
    printf("%d\n", V[P-1]);
  }
}

C++: #include "bits/stdc++.h"

#define REP(i,n) for(ll i=0;i<n;++i)
#define RREP(i,n) for(ll i=n-1;i>=0;--i)
#define FOR(i,m,n) for(ll i=m;i<n;++i)
#define RFOR(i,m,n) for(ll i=n-1;i>=m;--i)
#define ALL(v) (v).begin(),(v).end()
#define PB(a) push_back(a)
#define UNIQUE(v) v.erase(unique(ALL(v),v.end()));
#define DUMP(v) REP(i, (v).size()) { cout << v[i]; if (i != v.size() - 1)cout << " "; else cout << endl; }
#define INF 1000000001ll
#define MOD 1000000007ll
#define EPS 1e-9

const int dx[8] = { 1,1,0,-1,-1,-1,0,1 };
const int dy[8] = { 0,1,1,1,0,-1,-1,-1 };


using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
///(?´????????`)(?´????????`)(?´????????`)(?´????????`)(?´????????`)(?´????????`)///
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	vi prime = { 2 };
	FOR(i, 3,150000) {
		int flag = 1;
		REP(j, prime.size()) {
			if (i%prime[j] == 0)flag = 0;
		}
		if (flag)prime.push_back(i);
	}

	int n, p;
	while (1) {
		cin >> n >> p;
		if (n == -1)break;
		int c = lower_bound(ALL(prime), n) - prime.begin();
		vi v(p*p);
		REP(i, p) {
			REP(j, p) {
				v[i*p + j] = prime[i] + prime[j];
			}
		}
		sort(ALL(v));
		cout << v[p - 1] << endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
const int N = 400000;
int for_erat[N];
vector<int> prime;
vector<int> v;
vector<int> res;


void erat(){
    for(int i = 0; i < N; i++){
        for_erat[i] = 1;
    }
    for(int i = 2; i < sqrt(N); i++){
        if(for_erat[i]){
            for(int j = 0; i * (j + 2) < N; j++){
                for_erat[i *(j + 2)] = 0;
            }
        }
    }

    for(int i = 2; i < N; i++){
        if(for_erat[i]){
            prime.push_back(i);
        }
    }
}

int main(){
	erat();
	//for(int i = 0; i < 10; i++) cout << prime[i] << endl;
while(1){//start
	//init
	v.clear();
	res.clear();


	int n, p;
	cin >> n >> p;
	if(n == -1 and p == -1) break;

	//n以上の素数を15個見つける
	int idx = 0;
	while((int)v.size() != 20){
		if(prime[idx] > n) v.push_back(prime[idx]);
		idx++;
	}

	for(int i = 0; i < (int)v.size(); i++){
		for(int j = i; j < (int)v.size(); j++) res.push_back(v[i] + v[j]);
	}

	sort(res.begin(), res.end());
	//res.erase(unique(res.begin(), res.end()), res.end());

	cout << res[p-1] << endl;
	for(int i = 0; i < (int)res.size(); i++) cout << res[i] << endl;


}//end
	return 0;

}