#include<iostream>
#include<cstring>
#include<cmath>
#include<cstdio>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn=200010,maxm=4000010;
int a,b,c,d,t,pos[maxn],cnt=1,cur,fa[maxn],ch[maxn][26],dis[maxn],n,m,tot;
char s[maxn];
int add(int c,int p){cur=++cnt;dis[cur]=dis[p]+1;for(;p&&!ch[p][c];p=fa[p])ch[p][c]=cur;if(!p)fa[cur]=1;else{int q=ch[p][c];if(dis[q]==dis[p]+1)fa[cur]=q;else{int nt=++cnt;dis[nt]=dis[p]+1;memcpy(ch[nt],ch[q],sizeof(ch[0]));fa[nt]=fa[q];fa[q]=fa[cur]=nt;for(;p&&ch[p][c]==q;p=fa[p])ch[p][c]=nt;}}return cur;
}
vector<int>tong[maxn];
int root[maxn],siz[maxn],tim,last[maxn*2],pre[maxn*2],other[maxn*2],f[maxn][25],dfn[maxn],from[maxn];
void insert(int x,int y){++t;pre[t]=last[x];last[x]=t;other[t]=y;}
void dfs(int x){siz[x]=1;dfn[x]=++tim;from[tim]=x;for(int i=last[x];i;i=pre[i]){int v=other[i];f[v][0]=x;dfs(v);siz[x]+=siz[v];}
}
int jump(int x,int y){for(int i=20;i>=0;--i){if(dis[f[x][i]]>=y)x=f[x][i];}return x;
}
struct node{int l,r,v;
}tr[maxm];
void build(int pos,int l,int r,int &x){++tot;tr[tot]=tr[x];x=tot;++tr[x].v;if(l==r)return;int mid=l+r>>1;if(pos<=mid)build(pos,l,mid,tr[x].l);else build(pos,mid+1,r,tr[x].r);
}
int qs(int i,int j,int l,int r,int L,int R){if(r<L||l>R||r<l)return 0;if(l>=L&&r<=R)return tr[j].v-tr[i].v;int mid=l+r>>1;return qs(tr[i].l,tr[j].l,l,mid,L,R)+qs(tr[i].r,tr[j].r,mid+1,r,L,R);
}
int pd(int mid){int op=jump(pos[c],mid);return qs(root[dfn[op]-1],root[dfn[op]+siz[op]-1],1,n,a,b-mid+1);
}
int main(){//freopen("data.in","r",stdin);//freopen("data.out","w",stdout);int tmp=1;cin>>n>>m;scanf("%s",s+1);for(int i=n;i>=1;--i){tmp=add(s[i]-'a',tmp);pos[i]=tmp;tong[pos[i]].push_back(i);}for(int i=2;i<=cnt;++i)insert(fa[i],i);dfs(1);for(int j=1;j<=20;++j)for(int i=1;i<=cnt;++i){f[i][j]=f[f[i][j-1]][j-1];}for(int i=1;i<=tim;++i){int siz=tong[from[i]].size();root[i]=root[i-1];for(int j=0;j<siz;++j){build(tong[from[i]][j],1,n,root[i]);}}for(int i=1;i<=m;++i){scanf("%d%d%d%d",&a,&b,&c,&d);int l=1,r=min(d-c+1,b-a+1),ans=0;while(l<=r){int mid=l+r>>1;if(pd(mid))ans=mid,l=mid+1;else r=mid-1;}printf("%d\n",ans);}//fclose(stdin);//fclose(stdout);//system("pause");return 0;
}
/*
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*/