#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <map>
#include <queue>
#include <cmath>
#include <vector>
using namespace std;
/*const int num = 16, ud[] = { -1, 0, 1, 0 }, lr[] = { 0, -1, 0, 1 }, nd = 4;
//const char wa[] = { 'u', 'l', 'd', 'r' };
int md[num][num];
int lm;
struct puzzle {
	int sp, p[num], mdp, cost;
	//string way;
	bool operator < (const puzzle &pu) const {
		for (int i = 0; i < num; i++) {
			if (p[i] == pu.p[i]) continue;
			return p[i] < pu.p[i];
		}
		return false;
	}
};
struct state {
	puzzle pu;
	//int es = pu.mdp + pu.cost;
	bool operator < (const state &s) const {
		return pu.mdp + pu.cost > s.pu.mdp + s.pu.cost;
		//return es > s.es;
	}
};
puzzle pu; 
int astar(puzzle pz) {
	priority_queue<state> pq;
	map<puzzle, bool> m;
	state s;
	s.pu = pz;
	//s.es = pu.mdp;
	pq.push(s);
	state st, st1;
	puzzle p;
	int tx, ty, ns;
	while (!pq.empty()) {
		st = pq.top(); pq.pop();
		p = st.pu;
		//cout << "cost" <<  p.cost << endl;
		//cout << "mfp" << p.mdp << endl;
		if (!p.mdp) return p.cost;
		puzzle tmp;
		m[p] = true;
		int sx = p.sp / nd;
		int sy = p.sp % nd;
		for (int r = 0; r < nd; r++) {
			tx = sx + ud[r];
			ty = sy + lr[r];
			tmp = p;
			if (tx >= nd || tx < 0 || ty >= nd || ty < 0) continue;
			ns = tx * nd + ty;
			tmp.mdp = p.mdp - md[ns][p.p[ns] - 1] + md[sx*nd + sy][p.p[ns] - 1];
			tmp.sp = ns;
			swap(tmp.p[ns], tmp.p[sx * nd + sy]);
			tmp.cost = p.cost + 1;
			//cout << tmp.cost << endl;
			if (!m[tmp]) {
				st1.pu = tmp;
				//st1.es = tmp.cost + tmp.mdp;
				pq.push(st1);
			}
		}
	}
}

/*int astar() {
	priority_queue<state> pq;
	map<puzzle, bool> m;
	state s;
	s.pu = pu;
	//s.es = pu.mdp;
	pq.push(s);
	state st, st1;
	puzzle p;
	int tx, ty, ns;
	while (!pq.empty()) {
		st = pq.top(); pq.pop();
		p = st.pu;
		//cout << "cost" <<  p.cost << endl;
		//cout << "mfp" << p.mdp << endl;
		if (!p.mdp) return p.cost;
		puzzle tmp;
		m[p] = true;
		int sx = p.sp / nd;
		int sy = p.sp % nd;
		for (int r = 0; r < nd; r++) {
			tx = sx + ud[r];
			ty = sy + lr[r];
			tmp = p;
			if (tx >= nd || tx < 0 || ty >= nd || ty < 0) continue;
			ns = tx * nd + ty;
			tmp.mdp = p.mdp - md[ns][p.p[ns] - 1] + md[sx*nd + sy][p.p[ns] - 1];
			tmp.sp = ns;
			swap(tmp.p[ns], tmp.p[sx * nd + sy]);
			tmp.cost = p.cost + 1;
			//cout << tmp.cost << endl;
			if (!m[tmp]) {
				st1.pu = tmp;
				//st1.es = tmp.cost + tmp.mdp;
				pq.push(st1);
			}
		}
	}
}*/

/*int main() {
	int sum = 0;
	for (int i = 0; i < num; i++) {
		cin >> pu.p[i];
		if (!pu.p[i])  pu.sp = i;
	}
	for (int i = 0; i < num; i++)
		for (int j = 0; j < num; j++)
			md[i][j] = abs(i / nd - j / nd) + abs(i%nd - j%nd);
	for (int i = 0; i < num; i++) {
		if (pu.p[i] == 0) continue;
		sum += md[i][pu.p[i] - 1];
	}
	pu.mdp = sum;
	pu.cost = 0;
	cout << astar(pu) << endl;
	return 0;
}*/
#include<iostream>
#include <cstdio>
#include <cmath>
#include <queue>
#include <map>
using namespace std;

static const int N = 4;
static const int N2 = 16;

static const int dx[4] = { 0,-1,0,1 };
static const int dy[4] = { 1,0,-1,0 };
static const int dir[4] = { 'r','u','l','d' };
int MDT[N2][N2];

struct Puzzle {
	int f[N2], space, MD;
	int cost;

	bool operator < (const Puzzle &p) const {
		for (int i = 0; i < N2; ++i) {
			if (f[i] == p.f[i]) continue;
			return f[i] < p.f[i];
		}
		return false;
	}
};

struct State {
	Puzzle puzzle;
	int estimated;
	bool operator < (const State &s) const {
		return estimated > s.estimated;
	}
};

int getALLMD(Puzzle pz) {
	int sum = 0;
	for (int i = 0; i < N2; ++i) {
		if (pz.f[i] == N2) continue;
		sum += MDT[i][pz.f[i] - 1];
	}
	return sum;
}

int astar(Puzzle s) {
	priority_queue<State> PQ;
	s.MD = getALLMD(s);
	s.cost = 0;
	map<Puzzle, bool> V;
	Puzzle u, v;
	State initial;
	initial.puzzle = s;
	initial.estimated = getALLMD(s);
	PQ.push(initial);

	while (!PQ.empty()) {
		State st = PQ.top(); PQ.pop();
		u = st.puzzle;

		if (u.MD == 0) return u.cost;
		V[u] = true;

		int sx = u.space / N;
		int sy = u.space % N;

		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;
			v = u;

			v.MD -= MDT[tx * N + ty][v.f[tx * N + ty] - 1];
			v.MD += MDT[sx * N + sy][v.f[tx * N + ty] - 1];

			swap(v.f[sx * N + sy], v.f[tx * N + ty]);
			v.space = tx * N + ty;
			if (!V[v]) {
				v.cost++;
				State news;
				news.puzzle = v;
				news.estimated = v.cost + v.MD;
				PQ.push(news);
			}
		}
	}
	return -1;
}

int main() {
	for (int i = 0; i < N2; ++i) {
		for (int j = 0; j < N2; ++j) {
			MDT[i][j] = abs(i / N - j / N) + abs(i % N - j % N);
		}
	}
	Puzzle in;

	for (int i = 0; i < N2; ++i) {
		cin >> in.f[i];
		if (in.f[i] == 0) {
			in.f[i] = N2;
			in.space = i;
		}
	}
	cout << astar(in) << endl;
	return 0;
}

Measured memory_bytes: 257688