#include<iostream>
#include<cstdio>
#include<algorithm>
#include<fstream>
using namespace std;
long long n,k,a[101],p[101],e,m,g,br,i,time1;
string s[101];
void check_str()
{
    for(long long i=2; i<=n; i++)
    {
        int g1=0;
        for(long long j=1; j<=k; j++)
        {
            g1^=(s[i][a[j]]-'0');
        }
        if(g1!=p[i]) {e=1; return ;}
    }
}
void form_string(long long t, long long j)
{
    if(j>m&&t>0) return ;
    else if(t==0&&g==p[1]) {e=0; time1+=n*m; check_str(); if(e==1) e=0; else e=1; return ;}
    for(long long i=j+1; i<=m-1; i++)
    {
        time1++;
        a[++br]=i; int g1=g; g^=(s[1][i]-'0');
        form_string(t-1,i);
        if(time1>100000000) {return ;}
        if(e==1) return ;
        br--; g=g1;
    }
}
int main()
{
    ifstream cin;
    ofstream cout;
    cin.open("bits.in");
    cout.open("bits.out");
	cin>>n>>k;
	for(i=1; i<=n; i++)
	{
	    cin>>s[i];
	    m=s[i].size();
	    cin>>p[i];
	}
	for(i=k; i>=1; i--)
	{
	    form_string(i,-1);
	    if(e==1) break;
	}
	if(e==0) {cout<<-1<<endl;}
	else
	{
	    cout<<br<<endl;
	    for(i=1; i<=br-1; i++)
	    {
	        cout<<a[i]<<" ";
	    }
	    cout<<a[br]<<endl;
	}
	cin.close();
	cout.close();
	return 0;
}