#include <bits/stdc++.h>#define PI acos(-1)const int N = 500010;using namespace std;struct EX
{double real,i;EX operator+(const EX tmp)const{return (EX){real+tmp.real, i+tmp.i};};EX operator-(const EX tmp)const{return (EX){real-tmp.real, i-tmp.i};};EX operator*(const EX tmp)const{return (EX){real*tmp.real - i*tmp.i, real*tmp.i + i*tmp.real};};
};int R[N<<2];void DFT(EX a[],int n,int tp_k)
{for(int i=0;i<n;i++) if(i<R[i]) swap(a[i],a[R[i]]);for(int d=1;d<n;d<<=1){EX wn = (EX){cos(PI/d), sin(PI/d)*tp_k};for(int i=0;i<n;i += (d<<1)){EX wt = (EX){1,0};for(int k=0;k<d;k++, wt = wt*wn){EX A0 = a[i+k], A1 = wt * a[i+k+d];a[i+k] = A0+A1;a[i+k+d] = A0-A1;}}}if(tp_k==-1)for(int i=0;i<n;i++) a[i] = (EX){a[i].real/n, a[i].i/n};
}EX A[N<<2],B[N<<2],C[N<<2];
char S[N];
int n;
bool del[N],ans[N];void calc(char ch1,char ch2,int tot)
{for(int i=0;i<tot;i++) A[i] = B[i] = (EX){0,0};for(int i=0;i<n;i++) if(S[i]==ch1) B[i] = (EX){1,0};for(int i=1;i<=n;i++) if(S[n-i]==ch2) A[i] = (EX){1,0};DFT(A,tot,1);DFT(B,tot,1);for(int i=0;i<tot;i++) C[i] = A[i]*B[i];DFT(C,tot,-1);for(int i=0;i<n;i++){int tmp = (int)(C[2*n-i-1].real+0.5);if(tmp) del[i] = 1;}
}int main()
{int T;cin>>T;while(T--){scanf("%d%s",&n,S);int L = 0,tot;while((1<<L)<n+n) L++;tot = (1<<L);for(int i=1;i<tot;i++) R[i]=(R[i>>1]>>1)|((i&1)<<(L-1));for(int i=0;i<n;i++) del[i] = 0, ans[i+1] = 0;calc('V','K',tot);calc('K','V',tot);for(int i=n-1;i>=0;i--) if(!del[i]) ans[n-i-1] = 1;ans[n] = 1;int cnt = 0;for(int i=1;i<=n;i++){for(int j=i+i;j<=n;j+=i) ans[i] &= ans[j];if(ans[i]) cnt++;}printf("%d\n",cnt);for(int i=1;i<=n;i++) if(ans[i]) printf("%d ",i);printf("\n");}return 0;
}