#include<bits/stdc++.h>
#define int long long
#define fo(iii,aaa,bbb) for(int iii=aaa;iii<=bbb;iii++)
#define foa(ppp,aaa) for(auto ppp:aaa)
#define pb push_back
#define ls (p<<1)
#define rs (p<<1|1)
#define mid ((l+r)>>1)
#define N (114514)
using namespace std;

int n,q;
char c[N];

signed main(){
    freopen("Time.in","r",stdin);freopen("Time.out","w",stdout);
    ios::sync_with_stdio(0);cin.tie(0);
    cin>>n>>q;
    fo(i,1,n)cin>>c[i];
    while(q--){
        int l,r;
        cin>>l>>r;
        int ans=-1;
        fo(i,l,r-2){
            for(int k=r;k>=i+2;k--){
                fo(j,i+1,k-1){
                    if(c[j]==c[k]&&c[i]!=c[j]){
                        ans=max(ans,(j-i)*(k-j));
                    }
                }
            }
        }
        cout<<ans<<"\n";
    }
    return 0;
}