#include<bits/stdc++.h>

 using namespace std;

 typedef unsigned long long ll;

 const int N=4e5+,M=1e9+;

 int n,m,ch[N][],siz[N],re[N],val[N],tot,rt;

 ll h1[N],h2[N],pm[N];

 char s[N];

 #define l(u) ch[u][0]

 #define r(u) ch[u][1]

 #define mid ((l+r)>>1)

 int newnode(int x) {int u=++tot; l(u)=r(u)=re[u]=,siz[u]=,val[u]=h1[u]=h2[u]=x; return u;}

 void pu(int u) {

     siz[u]=siz[l(u)]+siz[r(u)]+;

     h1[u]=h1[l(u)]*pm[siz[r(u)]+]+val[u]*pm[siz[r(u)]]+h1[r(u)];

     h2[u]=h2[r(u)]*pm[siz[l(u)]+]+val[u]*pm[siz[l(u)]]+h2[l(u)];

 }

 void rv(int u) {swap(l(u),r(u)),swap(h1[u],h2[u]),re[u]^=;}

 void pd(int u) {if(re[u])re[u]=,rv(l(u)),rv(r(u));}

 void sp(int w,int k,int& u,int& v) {

     if(!w) {u=v=; return;}

     pd(w);

     if(k>=siz[l(w)]+)u=w,sp(r(w),k-(siz[l(w)]+),r(u),v),pu(u);

     else v=w,sp(l(w),k,u,l(v)),pu(v);

 }

 void mg(int& w,int u,int v) {

     if(!u||!v) {w=u|v; return;}

     if(rand()%(siz[u]+siz[v])<siz[u])pd(u),w=u,mg(r(w),r(u),v);

     else pd(v),w=v,mg(l(w),u,l(v));

     pu(w);

 }

 void ins(int& u,int p,int x) {

     int L,R;

     sp(u,p,L,R),mg(L,L,newnode(x)),mg(u,L,R);

 }

 void del(int& u,int p) {

     int L,M,R;

     sp(u,p,L,R),sp(L,p-,L,M),mg(u,L,R);

 }

 void rev(int& u,int l,int r) {

     int L,M,R;

     sp(u,r,L,R),sp(L,l-,L,M);

     rv(M);

     mg(L,L,M),mg(u,L,R);

 }

 ll H(int& u,int l,int r) {

     int L,M,R;

     sp(u,r,L,R),sp(L,l-,L,M);

     ll ret=h1[M];

     mg(L,L,M),mg(u,L,R);

     return ret;

 }

 int lcp(int& u,int L,int R) {

     int l=,r=n-R+,ret;

     while(l<=r) {

         if(H(u,L,L+mid-)==H(u,R,R+mid-))ret=mid,l=mid+;

         else r=mid-;

     }

     return ret;

 }

 void build(int& u,int l=,int r=n) {

     if(l>r)return;

     u=newnode(s[mid-]-''+);

     build(l(u),l,mid-),build(r(u),mid+,r),pu(u);

 }

 int main() {

     srand(time());

     pm[]=;

     for(int i=; i<N; ++i)pm[i]=pm[i-]*M;

     while(scanf("%d%d",&n,&m)==) {

         scanf("%s",s);

         tot=,build(rt);

         while(m--) {

             int f,a,b;

             scanf("%d%d",&f,&a);

             if(f!=)scanf("%d",&b);

             if(f==)ins(rt,a,b+),n++;

             else if(f==)del(rt,a),n--;

             else if(f==)rev(rt,a,b);

             else if(f==)printf("%d\n",lcp(rt,a,b));

         }

     }

     return ;

 }