#include<cstdio>

#include<cstring>

#include<algorithm>

using namespace std;

int rdn()

{

  int ret=;bool fx=;char ch=getchar();

  while(ch>''||ch<''){if(ch=='-')fx=;ch=getchar();}

  while(ch>=''&&ch<='')ret=ret*+ch-'',ch=getchar();

  return fx?ret:-ret;

}

int Mx(int a,int b){return a>b?a:b;}

int Mn(int a,int b){return a<b?a:b;}

const int N=1e5+,K=,M=N*K;

int n,sa[N],rk[N],tp[N],tx[N],ht[N][K],lg[N],bin[K];

int tot,ls[M],rs[M],sm[M],rt[N];

char s[N];

void Rsort(int n,int nm)

{

  for(int i=;i<=nm;i++)tx[i]=;

  for(int i=;i<=n;i++)tx[rk[i]]++;

  for(int i=;i<=nm;i++)tx[i]+=tx[i-];

  for(int i=n;i;i--)sa[tx[rk[tp[i]]]--]=tp[i];

}

void get_sa(int n)

{

  int nm=;

  for(int i=;i<=n;i++)tp[i]=i,rk[i]=s[i]-'a'+;

  Rsort(n,nm);

  for(int k=;;k<<=)

    {

      int tot=;

      for(int i=n-k+;i<=n;i++)tp[++tot]=i;

      for(int i=;i<=n;i++)

    if(sa[i]>k)tp[++tot]=sa[i]-k;

      Rsort(n,nm);memcpy(tp,rk,sizeof rk);

      nm=;rk[sa[]]=;

      for(int i=;i<=n;i++)//i=2!!!!not i=1

    {

      int u=sa[i]+k,v=sa[i-]+k;// if(u>n)u=0; if(v>n)v=0;

      rk[sa[i]]=(tp[sa[i]]==tp[sa[i-]]&&tp[u]==tp[v])?nm:++nm;

    }

      if(nm==n)break;

    }

}

void get_ht(int n)

{

  for(int i=,k=,j;i<=n;i++)

    {

      if(rk[i]==)continue;//

      for((k?k--:),j=sa[rk[i]-];i+k<=n&&j+k<=n&&s[i+k]==s[j+k];k++);

      //////i+k<=n&&j+k<=n

      ht[rk[i]][0]=k;

    }

  for(int i=;i<=n;i++)lg[i]=lg[i>>]+;

  bin[]=;for(int i=;i<=lg[n];i++)bin[i]=bin[i-]<<;

  //i<=lg[n] not bin[i-1]<lg[n]!!!(should bin[i-1]<n)

  for(int t=;t<=lg[n];t++)

    for(int i=;i+bin[t]-<=n;i++)

      ht[i][t]=Mn(ht[i][t-],ht[i+bin[t-]][t-]);

}

void ins(int &cr,int pr,int l,int r,int p)

{

  cr=++tot;ls[cr]=ls[pr];rs[cr]=rs[pr];sm[cr]=sm[pr]+;

  if(l==r)return; int mid=l+r>>;

  if(p<=mid)ins(ls[cr],ls[pr],l,mid,p);

  else ins(rs[cr],rs[pr],mid+,r,p);

}

int qry(int r1,int r2,int l,int r,int p)

{

  if(sm[r2]-sm[r1]==)return ;

  if(l==r)return l; int mid=l+r>>,d=;//d=0!!

  if(p>mid)d=qry(rs[r1],rs[r2],mid+,r,p);

  if(d)return d;

  return qry(ls[r1],ls[r2],l,mid,p);

}

int qry2(int r1,int r2,int l,int r,int p)

{

  if(sm[r2]-sm[r1]==)return ;

  if(l==r)return l; int mid=l+r>>,d=;

  if(p<=mid)d=qry2(ls[r1],ls[r2],l,mid,p);//qry2 not qry

  if(d)return d;

  return qry2(rs[r1],rs[r2],mid+,r,p);

}

int qry_ht(int l,int r)

{

  if(l==r)return n-sa[l]+;//////n-sa[l]+1 not n-l+1!!!

  int d=lg[r-l];

  return Mn(ht[l+][d],ht[r-bin[d]+][d]);//l+1!!!not l

}

int main()

{

  int Q;n=rdn();Q=rdn();scanf("%s",s+);//+1

  get_sa(n);get_ht(n);

  for(int i=;i<=n;i++)ins(rt[i],rt[i-],,n,rk[i]);

  int l1,r1,l2,r2;

  while(Q--)

    {

      l1=rdn();r1=rdn();l2=rdn();r2=rdn();

      int l=,r=Mn(r1-l1+,r2-l2+),ans=;

      while(l<=r)

    {

      int mid=l+r>>,d=r1-mid+;

      int p1=qry(rt[l1-],rt[d],,n,rk[l2]);

      int p2=qry2(rt[l1-],rt[d],,n,rk[l2]);

      int tmp=Mx((p1?qry_ht(p1,rk[l2]):),(p2?qry_ht(rk[l2],p2):));

      if(tmp>=mid)ans=mid,l=mid+;

      else r=mid-;

    }

      printf("%d\n",ans);

    }

  return ;

}