C++ :

#include<bits/stdc++.h>
using namespace std;

int a[100100],n,q,k;

int main() {
//	freopen("test9.in","r",stdin);
//	freopen("test9.out","w",stdout);

	cin>>n>>q;
    for(int i = 1;i <= n;i++){
    	cin>>a[i]; 
	}
	
	int l,r,mid;
	for(int i = 1;i <= q;i++){
		cin>>k;
		//找左右边界
		l = 1;r = n;
		//左边界 
		while(l <= r){
			mid = (l+r)>>1;
			if(k <= a[mid]) r = mid - 1;
			else l = mid + 1; 
		} 
		
		if(a[l] == k) cout<<l<<" ";
		else cout<<-1<<" ";
		
		l = 1;r = n;
		//右边界
		while(l <= r){
			mid = (l+r)>>1;
			if(k >= a[mid]) l = mid + 1;
			else r = mid - 1;
		} 
		
		if(a[r] == k) cout<<r<<endl;
		else cout<<-1<<endl;
	}
	
	return 0;
}