#include<stdio.h>
#include<string.h>
#include<malloc.h>
#define ALL 362880

int fac[9] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320};

//0 for not appeared, 1 for appeared in future, 2 for passed
char flag[ALL];


class node
{
public:
    //f = g + h is the evaluation func
    int g;    //steps
    int zero;
    char s[9];
    char last;
};
node states[ALL];
node *head = states;
node *tail;

//notice how to get cantor func
int cantor(char *s)
{
    int sum = 1;

    for (int i = 0; i < 9; ++i) {
        int n = 0;

        for (int j = i + 1; j < 9 ; ++j) {
            if (s[j] < s[i]) {
                ++ n;
            }
        }

        sum += n * fac[8 - i];
    }

    return sum;
}
void init(char *s)
{
    memset(states, 0, sizeof(node)*ALL);
    memset(flag, 0, sizeof(flag));
    flag[cantor(s)] = 1;
    tail = head + 1;
    head -> g = 0;
    head ->last = -1;

    for (int i = 0; i < 9; ++i) {
        if (s[i] == '0') {
            head -> zero = i;
        }

        head->s[i] = s[i];
    }
}

int move()
{
    while (head != tail) {
        node *tmp = head;
        ++head;

        if (cantor(tmp->s) == ALL)
            return tmp -> g;

        flag[cantor(tmp -> s)] = 1;
        int dir[4] = {-3, 1, 3, -1};

        if (tmp -> last != -1)
            dir[tmp-> last] = 0;

        if (tmp -> zero < 3) dir[0] = 0;

        if (tmp -> zero > 5) dir[2] = 0;

        if ((tmp -> zero) % 3 == 0) dir[3] = 0;

        if ((tmp -> zero) % 3 == 2) dir[1] = 0;

        for (int i = 0; i < 4; ++i) {
            if (dir[i] != 0) {
                *tail = * tmp;
                int p = tail ->zero;
                tail -> zero = p + dir[i];
                tail -> s[p] = tmp -> s[p + dir[i]];
                tail -> s[p + dir[i]] = '0';
                int pn = cantor(tail -> s);

                if (flag[pn] == 0) {
                    tail -> g += 1;
                    tail->last = (2 + i) % 4; //һβܷ,ƶ2+i%4
                    ++tail;
                    flag[pn] = 1;
                }
            }
        }
    }
}
char readChar()
{
    char c = ' ';

    while (c == ' ' || c == '\n')
        c = getchar();

    return c;
}
int main(void)
{
    // char s[10] = "876543210";
    char s[9];

    for (int i = 0 ; i < 9; ++i) {
        s[i] = readChar();
    }

    init(s);
    printf("%d\n", move());
    return 0;
}