#include <bits/stdc++.h>
using namespace std;
#define ios ios::sync_with_stdio(false), cin.tie(nullptr);
#define endl '\n';
int dx[] = {0, 0, 0, 1, -1}, dy[] = {0, 1, -1, 0, 0};
bool flag = false;
int sx, sy;
const int goal[6][6] = {
    {0, 0, 0, 0},
    {0, 1, 2, 3},
    {0, 8, 0, 4},
    {0, 7, 6, 5},
};
int mp[5][5];
int value()
{
    int cnt = 0;
    for (int i = 1; i <= 3; i++)
    {
        for (int j = 1; j <= 3; j++)
        {
            if (mp[i][j] != goal[i][j])
            {
                cnt++;
            }
        }
    }
    return cnt;
}
int safe(int x, int y)
{
    if (x > 3 || x < 1 || y > 3 || y < 1)
    {
        return 0;
    }
    return 1;
}
void A_star(int dep, int x, int y, int maxdep)
{
    if (dep == maxdep)
    {
        if (!value())
        {
            flag = true;
            return;
        }
    }
    for (int i = 1; i <= 4; i++)
    {
        int xx = x + dx[i];
        int yy = y + dy[i];
        if (!safe(xx, yy))
        {
            continue;
        }
        swap(mp[x][y], mp[xx][yy]);
        int val = value();
        if (val  + dep <= maxdep)//估值函数
            A_star(dep + 1, xx, yy, maxdep);
        swap(mp[x][y], mp[xx][yy]);
    }
}
int main()
{
    ios;
    string s;
    int tot = 0;
    cin >> s;
    for (int i = 1; i <= 3; i++)
    {
        for (int j = 1; j <= 3; j++)
        {

            mp[i][j] = s[tot++] - '0';
            if (mp[i][j] == 0)
            {
                sx = i, sy = j;
            }
        }
    }
    if (!value())
    {
        cout << 0 << endl;
        return 0;
    }
    for (int i = 0;; i++)
    {
        A_star(0, sx, sy, i);
        if (flag)
        {
            cout << i << endl;
            return 0;
        }
    }

    return 0;
}