#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<utility>
#include<vector>
#define N 100005
#define int long long
#define mem(x) memset(x,0,sizeof(x))
#define fo(i,l,r) for(int i=l;i<=r;i++)
#define rf(i,r,l) for(int i=r;i>=l;i--)
using namespace std;
int n,m,k,a[N],op,ans,x,y,z;
char c[N];
vector<int>v[26];
void swap(int &x,int &y){int t=x;x=y;y=t;}
int max(int x,int y){return x>y?x:y;}
int min(int x,int y){return x<y?x:y;}
void ckmax(int &x,int y){if(y>x)x=y;}
void ckmin(int &x,int y){if(y<x)x=y;}
int read(){
    int sum=0;bool f=0;char c=getchar();
    for(;c<48||c>57;c=getchar())if(c==45)f=1;
    for(;c>=48&&c<=57;c=getchar())sum=sum*10+(c&15);
    return f?-sum:sum;
}
signed main(){
    freopen("Time.in","r",stdin);freopen("Time.out","w",stdout);
    n=read();m=read();
    scanf("%s",c+1);
    fo(i,1,n)a[i]=c[i]-97;
    fo(i,1,n)v[a[i]].push_back(i);
    while(m--){
        x=read();y=read();
        int ans=-1;
        fo(i,0,25){
            if(v[i].empty())continue;
            int l=0,r=v[i].size()-1,mid;
            while(l<r){
                mid=l+r+1>>1;
                if(v[i][mid]<=y)l=mid;
                else r=mid-1;
            }
            int lp=y+1,rp=v[i][l],hs=l;
            if(rp>y||rp<x)continue;
            if(a[x]!=i)lp=x;
            else
                fo(j,0,25){
                    if(j==i||v[j].empty())continue;
                    l=0;r=v[j].size()-1;
                    while(l<r){
                        mid=l+r>>1;
                        if(v[j][mid]>=x)r=mid;
                        else l=mid+1;
                    }
                    if(v[j][l]>=x)ckmin(lp,v[j][l]);
                }
            if(lp>rp)continue;
            l=0;r=hs;
            while(l<r){
                mid=l+r>>1;
                if(v[i][mid]>lp)r=mid;
                else l=mid+1;
            }
            if(l==hs)continue;
            r=hs-1;
            while(l<r){
                mid=l+r>>1;
                if(rp-v[i][mid]<=v[i][mid]-lp)r=mid;
                else l=mid+1;
            }
            ckmax(ans,(rp-v[i][l])*(v[i][l]-lp));
            if(l&&v[i][l-1]>lp)ckmax(ans,(rp-v[i][l-1])*(v[i][l-1]-lp));
        }
        printf("%lld\n",ans);
    }
    return 0;
}