#include<bits/stdc++.h>

using namespace std;

set<string> st;

int deal(string s){

    int len = s.size();

    for(int i = 0; i < len; ++i){

        if(s[i] == '0') return i;

    }

}

int bfs(){

    queue<string> q;

    queue<int> step;

    q.push("012345678");

    step.push(0);

    while(!q.empty()){

        string s = q.front();

        q.pop();

        int tmpstep = step.front();

        step.pop();

        int id = deal(s);

        string tmps = s;

        int tmpid = (id + 1) % 9;

        tmps[id] = s[tmpid];

        tmps[tmpid] = s[id];

        if(!st.count(tmps)){

            if(tmps == "087654321") return tmpstep + 1;

            st.insert(tmps);

            q.push(tmps);

            step.push(tmpstep + 1);

        }

        tmpid = (id + 2) % 9;

        tmps = s;

        tmps[id] = s[tmpid];

        tmps[tmpid] = s[id];

        if(!st.count(tmps)){

            if(tmps == "087654321") return tmpstep + 1;

            st.insert(tmps);

            q.push(tmps);

            step.push(tmpstep + 1);

        }

        tmpid = (id + 8) % 9;

        tmps = s;

        tmps[id] = s[tmpid];

        tmps[tmpid] = s[id];

        if(!st.count(tmps)){

            if(tmps == "087654321") return tmpstep + 1;

            st.insert(tmps);

            q.push(tmps);

            step.push(tmpstep + 1);

        }

        tmpid = (id + 7) % 9;

        tmps = s;

        tmps[id] = s[tmpid];

        tmps[tmpid] = s[id];

        if(!st.count(tmps)){

            if(tmps == "087654321") return tmpstep + 1;

            st.insert(tmps);

            q.push(tmps);

            step.push(tmpstep + 1);

        }

    }

    return -1;

}

int main(){

    printf("%d\n", bfs());

    return 0;

}