#include<bits/stdc++.h>
using namespace std;
const int N=1e5+5;
mt19937 rnd(time(0));
int T,n,t[N],a[N<<1],ca,cnt;
char s[N];
queue<int>q,Q;
bool check(){
	for(int i=2;i<n;++i)t[i]=t[i-1]^t[i-2]^s[i-1]^1;
	if(s[0]^1^t[0]^t[1]^t[n-1]||s[n-1]^1^t[0]^t[n-2]^t[n-1])return false;
	return true;
}
void chg(int x){
	cnt-=!s[x];
	s[x]^=1;
	cnt+=!s[x];
	if(!s[x]&&t[x])q.push(x);
	if(!s[x])Q.push(x);
}
void Set(int x){
	t[x]^=1;
	chg(x),chg((x+n-1)%n),chg((x+1)%n);
	a[++ca]=x+1;
}
void solve(){
	scanf("%d",&n);
	scanf("%s",s),ca=cnt=0;
	while(!Q.empty())Q.pop();
	while(!q.empty())q.pop();
	for(int i=0;i<n;++i){
		s[i]^=48;
		if(!s[i])Q.push(i),++cnt;
	}
	for(t[0]=0;t[0]<2;++t[0])for(t[1]=0;t[1]<2;++t[1])if(check()){
		for(int i=0;i<n;++i)if(!s[i]&&t[i])q.push(i);
		while(cnt){
			if(!q.empty()){
				int u=q.front();
				q.pop();
				if(!t[u]||s[u])continue;
				Set(u);
				continue;
			}
			int u=Q.front();
			Q.pop();
			if(s[u])continue;
			Set(u);
		}
		printf("%d\n",ca);
		for(int i=1;i<=ca;++i)printf("%d%c",a[i]," \n"[i==ca]);
		return;
	}
	puts("0");
}
int main(){
	scanf("%d",&T);
	while(T--)solve();
	return 0;
}