#include <iostream>

using namespace std;

int n,k;
int a[1001];

int main()
{
    cin>>n>>k;
    for(int i=1;i<=n;++i)
        cin>>a[i];
    int start1,start2;
    bool eBun;
    for(int i=1;i<k;++i){
        start1=(i-1)*(n/k)+1;
        for (int j=i+1;j<=k;++j){
            start2=(j-1)*(n/k)+1;
            eBun=1;
            for(int p=0;p<n/k;++p){
                if(a[start1+p]!=a[start2+p]){
                eBun=0;
                break;
            }
        }
    if(eBun==1){
        cout<<i<<" "<<j;
        return 0;
        }
    }
}
cout<<"NU";
return 0;
}