Problem: Problem

Given the string $ S $ of length $ N $. Process the following query $ Q $ times.

Query
Let $ S [L: R] $ be a character string consisting of $ S $ from the $ L $ character to the $ R $ character (including both ends).
Represent $ S [L: R] $ as $ AXBXCX (1 \ leq | A |, | B |, | C |, | X |) $ using the appropriate strings $ A, B, C, X $ With that in mind, it prints the length of the longest of such $ X $.
However, if such $ X $ does not exist, 0 is output instead.

Constraints

The input satisfies the following conditions.

* $ 1 \ leq N, Q \ leq 2 \ times 10 ^ 5 $
* Each letter of $ S $ consists of a lowercase alphabet
* $ 1 \ leq L_i \ leq R_i \ leq N $

Input

The input is given in the following format.


$ N $ $ Q $
$ S $
$ L_1 $ $ R_1 $
$ L_2 $ $ R_2 $
$ \ vdots $
$ L_Q $ $ R_Q $


$ N, Q, L, R $ are all given as integers.
$ N $ and $ Q $ are given on the first line, separated by blanks.
The string $ S $ is given on the second line.
2 + $ i (1 \ leq i \ leq Q) $ L_i $ and $ R_i $ are given on the $ line separated by blanks. These represent $ L, R $ in the $ i $ th query.

Output

Print the longest $ X $ length on a single line for each query.

Examples

Input

12 3
itisansansan
1 12
5 12
6 7


Output

2
1
0


Input

20 2
sensanbyakusanjuusan
1 20
1 14


Output

3
1


Input

21 6
aaaabaaaabaaaaaaaaaab
1 21
10 21
10 18
4 16
11 21
1 6


Output

4
0
2
2
0
1

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


struct SuffixArray{
  string s;
  vector<int> sa,rev;

  SuffixArray(){}
  SuffixArray(const string &S):s(S){
    int n=s.size();
    s.push_back('$');
    sa.resize(n+1);
    iota(sa.begin(),sa.end(),0);
    sort(sa.begin(),sa.end(),
         [&](int a,int b){
           if(s[a]==s[b]) return a>b;
           return s[a]<s[b];
         });
    vector<int> c(n+1,0),r(n+1),cnt(n+1);
    for(int i=0;i<=n;i++) r[i]=s[i];
    for(int len=1;len<=n;len*=2){
      for(int i=0;i<=n;i++){
        c[sa[i]]=i;
        if(i>0 &&
           r[sa[i-1]]==r[sa[i]] &&
           sa[i-1]+len<=n &&
           r[sa[i-1]+len/2]==r[sa[i]+len/2]) c[sa[i]]=c[sa[i-1]];
      }
      iota(cnt.begin(),cnt.end(),0);
      copy(sa.begin(),sa.end(),r.begin());
      for(int i=0;i<=n;i++){
        int s1=r[i]-len;
        if(s1>=0) sa[cnt[c[s1]]++]=s1;
      }
      c.swap(r);
    }
    rev.resize(n+1);
    for(int i=0;i<=n;i++) rev[sa[i]]=i;
  }
  int operator[](int i) const{return sa[i];}

  bool lt_substr(string &t,int si,int ti){
    int sn=s.size(),tn=t.size();
    while(si<sn&&ti<tn){
      if(s[si]<t[ti]) return 1;
      if(s[si]>t[ti]) return 0;
      si++;ti++;
    }
    return si==sn&&ti<tn;
  }

  int lower_bound(string& t){
    int l=0,r=s.size();
    while(l+1<r){
      int m=(l+r)>>1;
      if(lt_substr(t,sa[m],0)) l=m;
      else r=m;
    }
    return r;
  }

  int upper_bound(string& t){
    t.back()++;
    int res=lower_bound(t);
    t.back()--;
    return res;
  }

  // O(|T|*log|S|)
  int count(string& T){
    return upper_bound(T)-lower_bound(T);
  }
};


struct LongestCommonPrefix{
  SuffixArray sa;

  vector<int> ht;
  vector< vector<int> > dat;
  LongestCommonPrefix(string &s):sa(s){
    int n=s.size();
    vector<int> lcp(n,0);

    int t=0;
    lcp[0]=0;
    for(int i=0;i<n;i++){
      int j=sa[sa.rev[i]-1];
      if(t>0) t--;
      for(;j+t<n&&i+t<n;t++){
        if(sa.s[j+t]!=sa.s[i+t]) break;
      }
      lcp[sa.rev[i]-1]=t;
    }

    int h=1;
    while((1<<h)<n) h++;
    dat.assign(h,vector<int>(n));
    ht.assign(n+1,0);
    for(int j=2;j<=n;j++) ht[j]=ht[j>>1]+1;

    for(int j=0;j<n;j++) dat[0][j]=lcp[j];
    for(int i=1,p=1;i<h;i++,p<<=1)
      for(int j=0;j<n;j++)
        dat[i][j]=min(dat[i-1][j],dat[i-1][min(j+p,n-1)]);
  }

  // a, b are indices for suffix array
  int query(int a,int b){
    assert(a!=b);
    if(a>b) swap(a,b);
    int l=b-a;
    return min(dat[ht[l]][a],dat[ht[l]][b-(1<<ht[l])]);
  }

  // a, b are indices for string
  int lcp(int a,int b){
    return query(sa.rev[a],sa.rev[b]);
  }
};


struct FullyIndexableDictionary{
  int len,blk;
  vector<unsigned> bit;
  vector<int> sum;

  FullyIndexableDictionary(){}
  FullyIndexableDictionary(int len)
    :len(len),blk((len+31)>>5),bit(blk,0),sum(blk,0){}

  void set(int k){
    bit[k>>5]|=1u<<(k&31);
  }

  void build(){
    sum[0]=0;
    for(int i=1;i<blk;i++)
      sum[i]=sum[i-1]+__builtin_popcount(bit[i-1]);
  }

  bool operator[](int k) const{
    return bool((bit[k>>5]>>(k&31))&1);
  }

  int rank(int k){
    return sum[k>>5]+__builtin_popcount(bit[k>>5]&((1u<<(k&31))-1));
  }

  int rank(bool v,int k){
    return (v?rank(k):k-rank(k));
  }

  int select(bool v,int k){
    if(k<0||rank(v,len)<=k) return -1;
    int l=0,r=len;
    while(l+1<r){
      int m=(l+r)>>1;
      if(rank(v,m)>=k+1) r=m;
      else l=m;
    }
    return r-1;
  }

  int select(bool v,int i,int l){
    return select(v,i+rank(v,l));
  }
};

template<class T,int MAXLOG>
struct WaveletMatrix{
  int len;
  FullyIndexableDictionary mat[MAXLOG];
  int zs[MAXLOG],buff1[MAXLOG],buff2[MAXLOG];
  static const T npos=-1;

  int freq_dfs(int d,int l,int r,T val,T a,T b){
    if(l==r) return 0;
    if(d==MAXLOG) return (a<=val&&val<b)?r-l:0;
    T nv=T(1)<<(MAXLOG-d-1)|val;
    T nnv=((T(1)<<(MAXLOG-d-1))-1)|nv;
    if(nnv<a||b<=val) return 0;
    if(a<=val&&nnv<b) return r-l;
    int lc=mat[d].rank(1,l),rc=mat[d].rank(1,r);
    return freq_dfs(d+1,l-lc,r-rc,val,a,b)
      +freq_dfs(d+1,lc+zs[d],rc+zs[d],nv,a,b);
  }

  WaveletMatrix(vector<T> data){
    len=data.size();
    vector<T> l(len),r(len);
    for(int dep=0;dep<MAXLOG;dep++){
      mat[dep]=FullyIndexableDictionary(len+1);
      int p=0,q=0;
      for(int i=0;i<len;i++){
        bool k=(data[i]>>(MAXLOG-(dep+1)))&1;
        if(k) r[q++]=data[i],mat[dep].set(i);
        else  l[p++]=data[i];
      }
      zs[dep]=p;
      mat[dep].build();
      swap(l,data);
      for(int i=0;i<q;i++) data[p+i]=r[i];
    }
  }

  T access(int k){
    T res=0;
    for(int dep=0;dep<MAXLOG;dep++){
      bool bit=mat[dep][k];
      res=(res<<1)|bit;
      k=mat[dep].rank(bit,k)+zs[dep]*dep;
    }
    return res;
  }

  // return the number of v in [0,k)
  int rank(T v,int k){
    int l=0,r=k;
    for(int dep=0;dep<MAXLOG;dep++){
      buff1[dep]=l;buff2[dep]=r;
      bool bit=(v>>(MAXLOG-(dep+1)))&1;
      l=mat[dep].rank(bit,l)+zs[dep]*bit;
      r=mat[dep].rank(bit,r)+zs[dep]*bit;
    }
    return r-l;
  }

  // return the position of k-th v
  int select(T v,int k){
    rank(v,len);
    for(int dep=MAXLOG-1;dep>=0;dep--){
      bool bit=(v>>(MAXLOG-(dep+1)))&1;
      k=mat[dep].select(bit,k,buff1[dep]);
      if(k>=buff2[dep]||k<0) return -1;
      k-=buff1[dep];
    }
    return k;
  }

  int select(T v,int k,int l){
    return select(v,k+rank(v,l));
  }

  // return k-th largest value in [l,r)
  T quantile(int l,int r,int k){
    if(r-l<=k||k<0) return -1;
    T res=0;
    for(int dep=0;dep<MAXLOG;dep++){
      int p=mat[dep].rank(1,l);
      int q=mat[dep].rank(1,r);
      if(q-p>k){
        l=p+zs[dep];
        r=q+zs[dep];
        res|=T(1)<<(MAXLOG-(dep+1));
      }else{
        k-=(q-p);
        l-=p;
        r-=q;
      }
    }
    return res;
  }

  T rquantile(int l,int r,int k){
    return quantile(l,r,r-l-k-1);
  }

  // return number of points in [left, right) * [lower, upper)
  int rangefreq(int left,int right,T lower,T upper){
    return freq_dfs(0,left,right,0,lower,upper);
  }

  pair<int, int> ll(int l,int r,T v){
    int res=0;
    for(int dep=0;dep<MAXLOG;dep++){
      buff1[dep]=l;buff2[dep]=r;
      bool bit=(v>>(MAXLOG-(dep+1)))&1;
      if(bit) res+=r-l+mat[dep].rank(bit,l)-mat[dep].rank(bit,r);
      l=mat[dep].rank(bit,l)+zs[dep]*bit;
      r=mat[dep].rank(bit,r)+zs[dep]*bit;
    }
    return make_pair(res,r-l);
  }

  int lt(int l,int r,T v){
    auto p=ll(l,r,v);
    return p.first;
  }

  int le(int l,int r,T v){
    auto p=ll(l,r,v);
    return p.first+p.second;
  }

  T succ(int l,int r,T v){
    int k=le(l,r,v);
    return k==r-l?npos:rquantile(l,r,k);
  }

  T pred(int l,int r,T v){
    int k=lt(l,r,v);
    return k?rquantile(l,r,k-1):npos;
  }
};

//INSERT ABOVE HERE

signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);

  int n,q;
  cin>>n>>q;
  string s;
  cin>>s;

  LongestCommonPrefix lcp(s);
  auto vs=lcp.sa.sa;
  auto rev=lcp.sa.rev;
  using WM = WaveletMatrix<int, 18>;
  WM wm(vs);

  auto calc=
    [&](int a,int b)->int{
      auto check=
        [&](int x)->int{
          int p=b-x;
          int pos=rev[p];
          int ll=-1,rr=-1;
          {
            int l=-1,r=pos;
            while(l+1<r){
              int m=(l+r)>>1;
              if(vs[m]+x<=n&&lcp.lcp(vs[m],p)>=x) r=m;
              else l=m;
            }
            ll=r;
          }
          {
            int l=pos,r=n+1;
            while(l+1<r){
              int m=(l+r)>>1;
              if(vs[m]+x<=n&&lcp.lcp(vs[m],p)>=x) l=m;
              else r=m;
            }
            rr=r;
          }
          // [ll, rr)
          int q=wm.pred(ll,rr,p-x);
          if(q==WM::npos||q-x<0) return 0;
          int k=wm.pred(ll,rr,q-x);
          if(k==WM::npos) return 0;
          return a<k;
        };

      int l=0,r=(b-a+2)/3;
      while(l+1<r){
        int m=(l+r)>>1;
        if(check(m)) l=m;
        else r=m;
      }
      return l;
    };

  for(int i=0;i<q;i++){
    int a,b;
    cin>>a>>b;
    a--;
    cout<<calc(a,b)<<"\n";
  }
  cout<<flush;
  return 0;
}