const readline = require('readline')

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});

let q = []
let dis_map = new Map()
// map get delete set has

let directions = [[0, -1], [0, 1], [-1, 0], [1, 0]] //上下左右

rl.on('line', line => {
    // 初始化状态
    q.push(line.split(' ').join(''))
     dis_map.set(q[0], 0);
})


rl.on('close', line => {

    let res
    while(q.length > 0){
        let t = q.shift()
        if(t == '12345678x') res = dis_map.get(t)

        const index = t.indexOf('x')
        const x = Math.floor(index / 3), y = index % 3

        directions.map(d => {
            const nx = x + d[0], ny = y + d[1] //下一个移动位置

            if(nx >= 0 && ny >= 0 && nx < 3 && ny < 3){
                let newPath = [...t]
                let tmp = newPath[nx*3+ny]
                newPath[nx*3+ny] = newPath[x*3+y]
                newPath[x*3+y] = tmp

                newPath = newPath.join('')

                if(!dis_map.has(newPath)){

                    dis_map.set(newPath, dis_map.get(t)+1)
                    q.push(newPath)
                }
            }
        })

    }

    console.log(res >= 0 ? res : -1)
})