#include<bits/stdc++.h>
using namespace std;
inline int re()
{
    int f=1,num=0;
    char c=getchar();
    while(c<'0'||c>'9'){if(c=='-') f=-1;c=getchar();}
    while(c>='0'&&c<='9') num=num*10+c-'0',c=getchar();
    return num*f;
}
const int N=100010,Z=30;
int n,q,ls,ls2,ls3;
long long ans;
int a[N];
int mark[Z][N];//vec[z],first_num>=n
char c[N];
vector<int> vec[Z];
int main()
{
    freopen("Time.in","r",stdin);
    freopen("Time.out","w",stdout);
    n=re();q=re();
    scanf("%s",c);
    for(int i=1;i<=n;i++) a[i]=c[i-1]-'a'+1,vec[a[i]].push_back(i);
    for(int z=1;z<=26;z++)
    {
        vec[z].push_back(n+1);
        for(int i=vec[z].size()-2;i+1;i--)for(int j=vec[z][i]+1;j<=vec[z][i+1];j++) mark[z][j]=i+1;
    }
    for(int i=1,l,r;i<=q;i++)
    {
        l=re();r=re();ans=-1;
        for(int x=1;x<=26;x++)
        {
            ls=mark[x][l];
            if(ls==vec[x].size()-1||vec[x][ls]>r) continue;
            for(int y=1;y<=26;y++)
            {
                if(x==y) continue;
                ls3=mark[y][r];
                if(vec[y][ls3]>r) ls3--;
                if(ls3<0) continue;
                ls2=mark[y][(vec[x][ls]+vec[y][ls3])/2];
                if(ls2)
                {
                    ls2--;
                    if(vec[x][ls]<vec[y][ls2]&&vec[y][ls2]<vec[y][ls3]) ans=max(ans,1ll*(vec[y][ls3]-vec[y][ls2])*(vec[y][ls2]-vec[x][ls]));
                    ls2++;
                }
                if(ls2==vec[y].size()-1) continue;
                if(vec[x][ls]<vec[y][ls2]&&vec[y][ls2]<vec[y][ls3]) ans=max(ans,1ll*(vec[y][ls3]-vec[y][ls2])*(vec[y][ls2]-vec[x][ls]));
                if(ls2!=vec[y].size()-1&&vec[x][ls]<vec[y][ls2]&&vec[y][ls2]<vec[y][ls3]) ans=max(ans,1ll*(vec[y][ls3]-vec[y][ls2])*(vec[y][ls2]-vec[x][ls]));
            }
        }
        printf("%lld\n",ans);
    }
    return 0;
}