#include<bits/stdc++.h> 
using namespace std;
int n, m;
int Q;
int l, r;
string s;
int main(){
	cin >> n >> m;
	cin >> s;
	for (int z = 0;z<m;z++){
		cin >> l >> r;
        int a, b, c, ans=-1;
        for (int x=l;x<=r;x++){
            if (s[x]=='a') a++;
            else if (s[x]=='b') b++;
            else c++;
        }
        if (a<2||b<2||c<2){
            cout << -1 << endl;
            continue;
        }
        for (int i = l;i<=r-2;i++){
            for (int j=i+1;j<=r-1;j++){
                for (int k=j+1;k<=r;k++){
                    int si=(j-i)*(k-j);
                    if ((s[j-1]==s[k-1])&&(s[j-1]!=s[i-1])){
                        ans=max(si, ans);
                    }
                }
            }
        }
        cout << ans << endl;
	}
	return 0;
}

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