//BOJ_2342_Dance Dance Revolution

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

class Main {
    static int[][][] dp;//dp[step][left][right]
    static int INF = 987654321;
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] s = br.readLine().split(" ");
        int[] list = new int[s.length];
        list[0] = 0;
        int size = list.length;
        for(int i=1;i<size;i++){
            if(s[i-1]=="0") break;
            list[i] = Integer.parseInt(s[i-1]);
        }

        dp = new int[size][5][5];
        for(int i=0;i<size;i++){
            for(int j=0;j<5;j++){
                Arrays.fill(dp[i][j], INF);
            }
        }

        dp[0][0][0] = 0;

        for(int step=0; step<size-1;step++){
            for(int i=0;i<5;i++){
                for(int j=0;j<5;j++){
                    int next = list[step+1];

                    if(i!=next){//i고정, j를 움직인다.
                        dp[step+1][i][next] = Math.min(dp[step+1][i][next], dp[step][i][j] + force(j, next));
                    }

                    if(j!=next){//j고정, i를 움직인다.
                        dp[step+1][next][j] = Math.min(dp[step+1][next][j], dp[step][i][j] + force(i, next));
                    }
                }
            }
        }

        int res = INF;
        for(int i=0;i<5;i++){
            for(int j=0;j<5;j++){
                res = Math.min(res, dp[size-1][i][j]);
            }
        }
        System.out.println(res);
    }

    public static int force(int i, int next){
        if(i==next) return 1;
        else if(i==0) return 2;
        else if(Math.abs(i-next)==2) return 4;
        return 3;
    }
}