#include <bits/stdc++.h>
using namespace std;

using ll=long long;

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)

#define pb push_back
#define eb emplace_back
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed

template<class t>using vc=vector<t>;
template<class t>using vvc=vc<vc<t>>;

using vi=vc<int>;

template<class t,class u>bool chmin(t&a,u b){
	if(a>b){a=b;return true;}
	else return false;
}
template<class t,class u>bool chmax(t&a,u b){
	if(a<b){a=b;return true;}
	else return false;
}


#define mp make_pair
#define a first
#define b second
using P=pair<int,int>;

constexpr int mod = 998244353;

void slv(){
	string s,t; cin>>s>>t;
	int n=s.size();
	vc<int>a(n),b(n);
	rep(i,n){
		a[i]=s[i]-'0'; if(i&1) a[i]^=1;
		b[i]=t[i]-'0'; if(i&1) b[i]^=1;
	}
	auto le=[](vc<int>vec){
		vc<int>ret;
		for(int i=0;i<vec.size();i++){
			if(vec[i] == 0) continue;
			for(int j=i-1;j>=0;j--){
				if(vec[j] == 1) break;
				swap(vec[j+1], vec[j]);
				ret.pb(j);
			}
		}
		return ret;
	};
	auto ze=[](vc<int>vec){
		vc<int>ret;
		while(1){
			int beg=1000000,las=-1;
			rep(i,vec.size()){
				if(vec[i]==1){
					chmin(beg,i);
					las=i;
				}
			}
			if(las == -1) return ret;
			for(int i=beg-1;i>=0;i--){
				swap(vec[i], vec[i+1]);
				ret.pb(i);
			}
			for(int i=las;i+1<vec.size();i++){
				swap(vec[i], vec[i+1]);
				ret.pb(i);
			}
			ret.pb(vec.size()-1);
			assert(vec[0] and vec[vec.size()-1]);
			vec[0] = 0;
			vec[vec.size()-1] = 0;
		}
	};
	if(n&1){
		int cnt=0;
		int one=0;
		rep(i,n)cnt+=a[i]-b[i];
		rep(i,n)one+=a[i];
		assert(cnt%2==0);
		if(one&1){
			rep(i,n){
				a[i]^=1;
				b[i]^=1;
			}
		}
		auto x = ze(a);
		auto y = ze(b);
		reverse(y.begin(), y.end());
		for(auto z:y) x.pb(z);
		cout<<x.size()<<'\n';
		for(auto e:x) cout<<e<<'\n';
	}
	
	else{
		int cnt=0;
		rep(i,n)cnt+=a[i]-b[i];
		assert(!cnt);
		auto x = le(a);
		auto y = le(b);
		reverse(y.begin(), y.end());
		for(auto z:y) x.pb(z);
		cout<<x.size()<<'\n';
		for(auto e:x) cout<<e<<'\n';
	}
}

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	
	int t;t=1;//cin>>t;
	rep(_,t) slv();
}