1 #include <stdio.h>
 2 #include <algorithm>
 3 #include <string.h>
 4 #include <set>
 5 #include <vector>
 6 #include <map>
 7 #include <vector>
 8 #include <queue>
 9 using namespace std;
10 const int N = (int)3e5+5;
11 
12 int n,k;
13 struct seg
14 {
15     int l, r, id;
16     bool operator < (const seg & A) const
17     {
18         return l < A.l;
19     }
20 }p[N];
21 
22 int main()
23 {
24     scanf("%d%d",&n,&k);
25     for(int i=1;i<=n;i++) {scanf("%d%d",&p[i].l,&p[i].r);p[i].id=i;}
26     sort(p+1,p+1+n);
27     priority_queue<int,vector<int>,greater<int> > Q;
28     int L = 0;
29     int ans = 0;
30     for(int i=1;i<=n;i++)
31     {
32         Q.push(p[i].r);
33         if(Q.size() > k) Q.pop();
34         if(Q.size() == k && ans < Q.top() - p[i].l + 1)
35         {
36             ans = Q.top() - p[i].l + 1;
37             L = p[i].l;
38         }
39     }
40     if(ans == 0)
41     {
42         puts("0");
43         int first = 0;
44         for(int i=1;i<=k;i++)
45         {
46             if(first) printf(" ");
47             else first = 1;
48             printf("%d",p[i].id);
49         }
50         puts("");
51     }
52     else
53     {
54         printf("%d\n",ans);
55         int first = 0;
56         for(int i=1;i<=n && k>0;i++)
57         {
58             int l = p[i].l, r = p[i].r;
59             if(l<=L && L+ans-1<=r)
60             {
61                 if(first) printf(" ");
62                 else first = 1;
63                 printf("%d",p[i].id);
64                 k--;
65             }
66         }
67         puts("");
68     }
69     return 0;
70 }