#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef tree<int,null_type,less<int>,rb_tree_tag,
tree_order_statistics_node_update> indexed_set;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
#define pb push_back
#define popb pop_back
#define pp pop_back
#define pf push_front
#define popf pop_front
#define all(x) (x).begin(),(x).end()
#define ff first
#define ss second
///#define int ll
int nx[4] = {0,0,1,-1}, ny[4] = {1,-1,0,0};
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;}
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);}
const int nax = 1e5 + 4;
int n, q, k = 1;
set<pii> st[4 * nax];
indexed_set nid;
int tr[nax], tl[nax], d[nax], sp[nax][20];
vpi v[2 * nax];
vi ef;
vi adj[nax], rev_adj[nax];
void build(int p, int l, int r)
{
if(l == r)
{
for(auto e: v[l])
st[p].insert(e);
return ;
}
build(2 * p, l, (l+r)/2);
build(2 *p + 1, (l+r)/2 + 1,r);
st[p] = st[2 * p];
for(auto e: st[2 * p + 1])
st[p].insert(e);
return ;
}
void update(int i)
{
int idx = i + k;
st[idx].erase({tl[i],i});
idx /= 2;
while(i)
{
st[idx].erase({tl[i],i});
i /= 2;
}
return;
}
void upd(int p, int l, int r, int i, int j, int idx)
{
if( i > j)
return ;
if(l >= i && r <= j)
{
for(auto e: st[p])
{
ef.pb(e.ss);
}
return ;
}
int m = (l+ r)/2;
upd(2 * p,l,m,i,min(j,m),idx);
upd(2*p+1,m+1,r,max(i,m+1),j,idx);
return ;
}
void dfs(int x, int p = -1)
{
d[x] = p ==-1? 0: d[p] + 1;
sp[x][0] = p== -1? x: p;
// cout << x << ' ' << d[x] << '\n';
for(auto e: adj[x])
{
if(e == x)
continue;
dfs(e,x);
}
}
int jump(int a, int k)
{
if(k < 0)
return -1;
for(int i = 0; i < 20; i ++)
if((1 << i) & k)
a = sp[a][i];
return a;
}
void solve()
{
cin >> n >> q;
for(int i = 0; i < n; i ++)
{
cin >> tl[i] >> tr[i];
nid.insert(tl[i]);
nid.insert(tr[i]);
}
k = 1;
while(k < (int)(nid.size()))
k = (k << 1);
for(int i = 0;i < n; i ++)
{
tl[i] = nid.order_of_key(tl[i]);
tr[i] = nid.order_of_key(tr[i]);
v[tr[i]].pb({tl[i],i});
}
build(1,0,k - 1);
bool vis[n]; memset(vis,false,sizeof(vis));
for(int i= 0; i < n;i ++)
{
upd(1,0,k-1,tl[i], tr[i],i);
for(auto u: ef)
if(u != i)
adj[i].pb(u);
ef.clear();
}
for(int i = 0; i < n; i++)
{
for(auto e: adj[i])
{
rev_adj[e].pb(i);
//cout << i << ' ' << e << '\n';
}
}
for(int i = 0; i < n ;i ++)
{
if(rev_adj[i].size() == 0)
dfs(i);
}
for(int j = 1; j < 20; j++)
for(int i= 0; i < n ;i ++)
sp[i][j] = sp[sp[i][j-1]][j-1];
while(q--)
{
int s, e;
cin >> s >> e;
s--; e--;
int c= jump(s,d[s] - d[e]);
if(c == e)
cout << d[s] - d[e] << '\n';
else
cout << "-1\n";
}
}
int32_t main()
{
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int tt = 1;
while(tt --)
solve();
}
