#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;
}