#pragma GCC optimize("O3,unroll-loops") #include <bits/stdc++.h> using namespace std; #define int long long #define ll long long #define pb push_back #define pii pair<int,int> #define sz(v) (int)v.size() #define fi first #define se second #define INF 1223372036854775807 #define INF2 122337203 #define MOD 998244353 #define cint(x) int x;cin>>x; #define cinarr(a,n) int a[n];for (int i=0;i<n;i++) cin>>a[i]; #define coutarr(a) for (auto d:a)cout<<d<<" "; cout<<endl; #define coutarrD(a) for (auto d:a) cout<<d.fi<<","<<d.se<<" "; cout<<endl; #define BERKAY_TUP ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL) #define endl '\n' #define ld long double #define mid (start+end)/2 #define vvi vector<vector<int>> int t=1; int interactive=0; int usaco=0; int testCase=0; pii tree[800023]; void update(int n,int start,int end,int x,pii v){ if (start>end || start>x || end<x) return; if (start>=x && end<=x){ if (v.fi==INF) tree[n]=v; else tree[n]=min(tree[n],v); return; } update(n*2,start,mid,x,v); update(n*2+1,mid+1,end,x,v); tree[n]=min(tree[n*2],tree[n*2+1]); } pii query(int n,int start,int end,int l,int r){ if (start>end || start>r || end<l) return {INF,-1}; if (start>=l && end<=r) return tree[n]; return min(query(n*2,start,mid,l,r),query(n*2+1,mid+1,end,l,r)); } void solve(){ int n,q; cin>>n>>q; vector<pii> v; set<int> s; for (int i=0;i<n;i++){ int x,y; cin>>x>>y; v.pb({x,y}); s.insert(x); s.insert(y); } vector<int> o; for (int d:s) o.pb(d); int h=sz(o); int z[n]; for (int i=1;i<=h;i++){ update(1,1,h,i,{INF,-1}); } for (int i=0;i<n;i++){ pii d=v[i]; int p=lower_bound(o.begin(),o.end(),d.se)-o.begin()+1; update(1,1,h,p,{d.fi,i}); } for (int i=0;i<n;i++){ pii d=v[i]; int p1=lower_bound(o.begin(),o.end(),d.fi)-o.begin()+1; int p2=lower_bound(o.begin(),o.end(),d.se)-o.begin()+1; pii c=query(1,1,h,p1,p2); if (c.fi<v[i].fi) z[i]=c.se; else z[i]=-1; } //coutarr(z); while (q--){ int a,b; cin>>a>>b; a--;b--; int ans=0; if (v[a].se>v[b].se){ cout<<"impossible"<<endl; continue; } if (a==b){ cout<<0<<endl; continue; } while (23){ if (v[b].fi<=v[a].se){ ans++; cout<<ans<<endl; break; } else if (z[b]!=-1){ b=z[b]; ans++; } else{ cout<<"impossible"<<endl; break; } } } } int32_t main(){ BERKAY_TUP; if (usaco){ freopen("team.in", "r", stdin); freopen("team.out", "w", stdout); } if (!interactive){ #ifdef Local freopen("in.txt", "r", stdin); freopen("out2.txt", "w", stdout); //freopen("wormsort.out", "w", stdout); #endif } if (t==1) solve(); else{ cin>>t; while (t--){testCase++;solve();} } return 0; }

events.cpp: In function 'int32_t main()':
events.cpp:125:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  125 |         freopen("team.in", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
events.cpp:126:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |         freopen("team.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~