Go: // BFS

package main

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

var scanner = bufio.NewScanner(os.Stdin)

var p = [15]int{}
var g = [13][4]int {
	// -1は存在しないマス目
	{2,-1,-1,-1},
	{2,5,-1,-1},{0,1,3,6},{2,7,-1,-1},
	{5,-1,-1,-1},{1,4,6,9},{2,5,7,10},{3,6,8,11},{7,-1,-1,-1},
	{5,10,-1,-1},{6,9,11,12},{7,10,-1,-1},
	{10,-1,-1,-1},
}

/*
　  ０ １ ２ ３ ４
 0 |／|／|  |／|／|
 1 |／|　|  |　|／|
 2 |　|　|  |　|　|
 3 |／|　|  |　|／|
 4 |／|／|  |／|／|
*/

var row = [13]int{0,1,1,1,2,2,2,2,2,3,3,3,4}
var col = [13]int{2,1,2,3,0,1,2,3,4,1,2,3,2}

type wolf struct {
	m [13]int
}

type pair struct {
	first wolf
	second int
}

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

func print_board(board [13]int) {
	fmt.Println("--------------------------")
	fmt.Printf("        [%2d]\n", board[0])
	fmt.Printf("    [%2d][%2d][%2d]\n", board[1], board[2], board[3])
	fmt.Printf("[%2d][%2d][%2d][%2d][%2d]\n", board[4], board[5], board[6], board[7], board[8])
	fmt.Printf("    [%2d][%2d][%2d]\n", board[9], board[10], board[11])
	fmt.Printf("        [%2d]\n", board[12])
	fmt.Println("--------------------------")
}

func main() {
	for scanner.Scan() {
		p1, _ := strconv.Atoi(scanner.Text())
		if p1 == -1 {
			break
		}
		p[0]= p1
		scanner.Scan()
		buf1 := strings.Split(scanner.Text(), " ")
		p2, _ := strconv.Atoi(buf1[0])
		p3, _ := strconv.Atoi(buf1[1])
		p4, _ := strconv.Atoi(buf1[2])
		p[1], p[2], p[3] = p2, p3, p4
		scanner.Scan()
		buf2 := strings.Split(scanner.Text(), " ")
		p5, _ := strconv.Atoi(buf2[0])
		p6, _ := strconv.Atoi(buf2[1])
		p7, _ := strconv.Atoi(buf2[2])
		p8, _ := strconv.Atoi(buf2[3])
		p9, _ := strconv.Atoi(buf2[4])
		p[4], p[5], p[6], p[7], p[8] = p5, p6, p7, p8, p9
		scanner.Scan()
		buf3 := strings.Split(scanner.Text(), " ")
		p10, _ := strconv.Atoi(buf3[0])
		p11, _ := strconv.Atoi(buf3[1])
		p12, _ := strconv.Atoi(buf3[2])
		p[9], p[10], p[11] = p10, p11, p12
		scanner.Scan()
		p13, _ := strconv.Atoi(scanner.Text())
		p[12] = p13
		S := make(map[wolf]struct{})
		st := wolf{}
		for i := 0; i < 13; i++ {
			st.m[i] = p[i]
		}
		Q := make([]pair, 0)
		S[st] = struct{}{}
		Q = append(Q, pair{st, 0})
		yet := true
		for len(Q) > 0 {
			at := Q[0].first
			// print_board(at.m)
			cost := Q[0].second
			Q = Q[1:]
			ok := true
			for i :=1; i < 12; i++ {
				if at.m[i] != i {
					ok = false
				}
			}
			if ok {
				// print_board(at.m)
				yet = false
				fmt.Println(cost)
				break
			}
			now := cost
			for i := 0; i < 13; i++ {
				if at.m[i] != 0 {
					now += abs(row[i]-row[at.m[i]]) + abs(col[i]-col[at.m[i]])
				}
			}
			if now > 20 {
				continue
			}
			for i := 0; i < 13; i++ {
				if at.m[i] == 0 {
					for j := 0; j < 4; j++ {
						if ^g[i][j] != 0 {
							at.m[i], at.m[g[i][j]] = at.m[g[i][j]], at.m[i]
							if _, ok := S[at]; !ok {
								S[at] = struct{}{}
								Q = append(Q, pair{at, cost+1})
							}
							at.m[i], at.m[g[i][j]] = at.m[g[i][j]], at.m[i]
						}
					}
				}
			}
		}
		if yet {
			fmt.Println("NA")
		}
	}
}

C++: #import<iostream>
#import<map>
#import<queue>
#import<cstdlib>
#import<cstring>
using namespace std;struct B{int z[2];char s[14];bool operator<(const B&r)const{return strcmp(s,r.s)<0;}};main(){int a[13][5]={{2,-1},{2,5,-1},{0,1,3,6,-1},{2,7,-1},{5,-1},{1,4,6,9,-1},{2,5,7,10,-1},{3,6,8,11,-1},{7,-1},{5,10,-1},{6,9,11,12,-1},{7,10,-1},{10,-1}},X[]={2,1,2,3,0,1,2,3,4,1,2,3,2},Y[]={0,1,1,1,2,2,2,2,2,3,3,3,4},v,d,s,i,j,t,u;B g={0,0,"0123456789:;0"};for(;;){map<B,int>m;queue<B>q;B b={i=-1,-1};for(;++i<13;!v?b.z[*b.z>=0]=i:0){cin>>v;if(v<0)return 0;b.s[i]=48+v;}b.s[13]=0;m[b]=1;for(q.push(b);!q.empty();q.pop()){B&b=q.front();if(!strcmp(b.s,g.s))break;for(d=i=0;i<13;v?d+=abs(X[v]-X[i])+abs(Y[v]-Y[i]):0,i++)v=b.s[i]-48;s=m[b];if(s+d<22)for(j=0;j<2;j++)for(i=0;~a[u=b.z[j]][i];i++){B n=b;t=n.z[j]=a[u][i];if(t-n.z[1-j]){swap(n.s[u],n.s[t]);int&r=m[n];if(!r)r=s+1,q.push(n);}}}printf(m[g]?"%d\n":"NA\n",m[g]-1);}}

C++: #include<bits/stdc++.h>
using namespace std;
   
typedef long long int64;
const int INF = 1 << 30;
   
vector< int > edge[13];
map< string, int > memo;
  
bool back(string str, int cnt){ //枝刈り大事だな
  static int dist[] = { 0, 2, 1, 2, 4, 3, 2, 3, 4, 2, 1, 2, 0};
  static int fuee[] = { 2, 0, 1, 2, 2, 1, 2, 3, 4, 2, 3, 4, 4};
  static int fuga[] = { 1, 1, 0, 1, 3, 2, 1, 2, 3, 3, 2, 3, 3};
  static int haaa[] = { 2, 2, 1, 0, 4, 3, 2, 1, 2, 4, 3, 2, 4};
  static int kira[] = { 3, 3, 2, 3, 3, 2, 1, 2, 3, 1, 0, 1, 1};
  
  if(cnt > 20) return true;
  int foo1 = 0, foo2 = 0, foo3 = 0, foo4 = 0, foo5 = 0;
  for(int i = 0; i < 13; i++){
    if(str[i] == '0') foo1 += dist[i];
    else if(str[i] == '1') foo2 += fuee[i];
    else if(str[i] == '2') foo3 += fuga[i];
    else if(str[i] == '3') foo4 += haaa[i];
    else if(str[i] == 'A') foo5 += kira[i];
  }
  return cnt + foo1 + foo2 + foo3 + foo4 + foo5 > 28;
}
  
  
int bfs(string mas){
  
  queue< string > que;
  map< string , int > used;
  que.push( mas );
  memo[mas] = 0;
  while(!que.empty()){
  
    string p = que.front(); que.pop();
    if(back( p, memo[p])) continue;
    if(p == "0123456789AB0") return memo[p];
  
    for(int i = 0; i < 13; i++){
      if(p[i] == '0') {
        for(int j = 0; j < edge[i].size(); j++){
          string next = p;
          swap( next[i], next[edge[i][j]]);
          if(memo.find(next) != memo.end()) continue;
          que.push( next );
          memo[next] = memo[p] + 1;
        }
      }
    }
  }
  return -1;
}
  
int main(){
  vector< int > mas(13);
  
  edge[0].push_back(2);
  edge[1].push_back(2); edge[1].push_back(4);
  edge[2].push_back(0); edge[2].push_back(1); edge[2].push_back(3); edge[2].push_back(6);
  edge[3].push_back(2); edge[3].push_back(7);
  edge[4].push_back(5);
  edge[5].push_back(1); edge[5].push_back(4); edge[5].push_back(6); edge[5].push_back(9);
  edge[6].push_back(2); edge[6].push_back(5); edge[6].push_back(7); edge[6].push_back(10);
  edge[7].push_back(3); edge[7].push_back(6); edge[7].push_back(8); edge[7].push_back(11);
  edge[8].push_back(7);
  edge[9].push_back(5); edge[9].push_back(10);
  edge[10].push_back(6); edge[10].push_back(9); edge[10].push_back(11); edge[10].push_back(12);
  edge[11].push_back(7); edge[11].push_back(10);
  edge[12].push_back(10);
  
  while(cin >> mas[0], mas[0] != -1){
    for(int i = 1; i < 13; i++){
      cin >> mas[i];
    }
  
    string start = "";
    for(int i = 0; i < 13; i++){
      if(mas[i] >= 10) start += (char)(mas[i] - 10 + 'A');
      else start += mas[i] + '0';
    }
    int ret = bfs(start);
    if(~ret) cout << ret << endl;
    else cout << "NA" << endl;
  
    memo.clear();
  }
}

C++: #define _USE_MATH_DEFINES
#define INF 10000000
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>
#include <limits>
#include <map>
#include <string>
#include <cstring>
#include <set>
#include <deque>
#include <bitset>
#include <list>

using namespace std;

typedef long long ll;
typedef pair<int,string> P;

static const double eps = 1e-8;

int main(){
  int a,b;
  while(~scanf("%d %d",&a,&b)){
    printf("%d\n",a-b);
  }
}