Problem: The goal of the 15 puzzle problem is to complete pieces on $4 \times 4$ cells where one of the cells is empty space.

In this problem, the space is represented by 0 and pieces are represented by integers from 1 to 15 as shown below.


1 2 3 4
6 7 8 0
5 10 11 12
9 13 14 15


You can move a piece toward the empty space at one step. Your goal is to make the pieces the following configuration in the shortest move (fewest steps).


1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 0


Write a program which reads an initial state of the puzzle and prints the fewest steps to solve the puzzle.

Constraints

* The given puzzle is solvable in at most 45 steps.

Input

The $4 \times 4$ integers denoting the pieces or space are given.

Output

Print the fewest steps in a line.

Example

Input

1 2 3 4
6 7 8 0
5 10 11 12
9 13 14 15


Output

8

Solution (in CPP):

Solution:
#include<stdio.h>
#include<iostream>
#include<cmath>
#include<string>
#include<cassert>
using namespace std;
#define N 4
#define N2 16
#define LIMIT 100
 
static const int dx[4] = {0, -1, 0, 1}; 
static const int dy[4] = {1, 0, -1, 0};
static const char dir[4] = {'r','u','l','d'};
int MMGo[N2][N2];
 
struct puzzle { int f[N2], space, MD; };
 
puzzle state;
int limit; 
int path[LIMIT];
 
int getAllMD(puzzle pz) {
    int sum = 0;
    for ( int i = 0; i < N2; i++ ) {
        if ( pz.f[i] == N2 ) continue;
        sum += MMGo[i][pz.f[i] - 1]; }
    return sum;
}
 
bool isSolved() {
    for ( int i = 0; i < N2; i++ ) if ( state.f[i] != i + 1 ) return false;
    return true;
}
 
bool dfs(int depth, int prev) {
    if ( state.MD == 0 ) return true;
    if ( depth + state.MD > limit ) return false;
     
    int sx = state.space / N;
    int sy = state.space % N;
    puzzle tmp;
     
    for ( int r = 0; r < 4; r++ ) {
        int tx = sx + dx[r];
        int ty = sy + dy[r];
        if ( tx < 0 || ty < 0 || tx >= N || ty >= N ) continue;
        if ( max(prev, r)-min(prev, r) == 2 ) continue;
        tmp = state;
         
        state.MD -= MMGo[tx * N + ty][state.f[tx * N + ty] - 1];
        state.MD += MMGo[sx * N + sy][state.f[tx * N + ty] - 1];
        swap(state.f[tx * N + ty], state.f[sx * N + sy]);
        state.space = tx * N + ty;
        if ( dfs(depth + 1, r) ) { path[depth] = r; return true; }
        state = tmp;
    }
    return false;
}
 
string iterative_deepening(puzzle in) {
    in.MD = getAllMD(in);
    for ( limit = in.MD; limit <= LIMIT; limit++ ) {
        state = in;
        if ( dfs(0, -100) ) {
            string ans = "";
            for ( int i = 0; i < limit; i++ ) ans += dir[path[i]];
            return ans;
        }
    }
     
    return "unsolvable";
     
}
int main() {
  int i,j;
    for (i = 0; i < N2; i++ )
        for (j = 0; j < N2; j++ )
            MMGo[i][j] = abs(i / N - j / N ) + abs(i % N - j % N);
    puzzle in;
     
    for (i = 0; i < N2; i++ ) {
        cin >> in.f[i];
        if ( in.f[i] == 0 ) {
            in.f[i] = N2;
            in.space = i;
             
        }
    }
    string ans = iterative_deepening(in);
    cout << ans.size() << endl;
    return 0;
     
}