#include<bits/stdc++.h>
using namespace std;
#define int long long
int lshu[100005][28],rshu[100005][28];
char xu[27]={'0','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
signed main(){
    freopen("Time.in","r",stdin);
    freopen("Time.out","w",stdout);
    
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n,m;
    cin>>n>>m;
    string a;
    cin>>a;
    for(int i = 1;i<=26;i++){
        int now=1;
        int shang=1;
        while(now<=n){
            while(a[now-1]!=xu[i] && now<=n){
                now++;
            }
            if(now>n)break;
            
            for(int j = shang;j<=now;j++){
                lshu[j][i]=now;
                //cout<<j<<" "<<i<<" "<<now<<" "<<lshu[j][i]<<endl;
            }
            shang=now+1;
            now++;
            
        }
        //cout<<shang<<endl;
        for(int j = shang;j<=n;j++){
            lshu[j][i]=-1;
        }
        
        
    }
    for(int i = 1;i<=26;i++){
        int now=n;
        int shang=n;
        while(now>=1){
            while(a[now-1]!=xu[i] && now>=1){
                now--;
            }
            if(now==0)break;
            
            for(int j = now;j<=shang;j++){
                rshu[j][i]=now;
                //cout<<j<<" "<<i<<" "<<now<<" "<<lshu[j][i]<<endl;
            }
            shang=now-1;
            now--;
            
        }
        //cout<<shang<<endl;
        for(int j = 1;j<=shang;j++){
            rshu[j][i]=-1;
        }
        
        
    }
    for(int i = 1;i<=m;i++){
        int l,r;
        cin>>l>>r;
        int ans=-1;
        for(int i = 1;i<=26;i++){
            
            //是否有该字母 
            if(lshu[l][i]==-1)continue;
            //该字母是否跃出询问边界 
            if(lshu[l][i]>=r)continue;
            int x=lshu[l][i];
            
            
            for(int j = 1;j<=26;j++){
                
                //该字母是否与字母i重合 
                if(i==j)continue;
                //是否有该字母 
                if(rshu[r][j]==-1)continue;
                //该字母是否跃出询问边界 
                if(rshu[r][j]<=l)continue;
                //该字母位置是否在字母i后面 
                if(rshu[r][j]<=x)continue;
                //这两个字母间距是否大于2 
                if((rshu[r][j]-x+1)<=2)continue;
                
                int y=rshu[r][j];
                
                int mid=(x+y)/2;
                
                
                
                
                
                
                
                int mt=lshu[mid][j];
                
                if(x<mt && mt<y){
                    ans=max(ans,(mt-x)*(y-mt));
                }
                
                mt=rshu[mid][j];
                if(x<mt && mt<y){
                    ans=max(ans,(mt-x)*(y-mt));
                }
                
                
                
            }
        }
        cout<<ans<<endl;
    }
    
    
    
    
    
    return 0;
}