#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define pbds tree<pair<ll, ll>, null_type, less<pair<ll,ll>>,rb_tree_tag, tree_order_statistics_node_update>
using namespace __gnu_pbds;
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;} // greatest common divisor (PGCD)
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);} // least common multiple (PPCM)
int dx[8] = {1, 0, 0, -1, 1, 1, -1, -1};
int dy[8] = {0, 1, -1, 0, 1, -1, -1, 1};
#define endl "\n"
#define ss second
#define ff first
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define vi vector<int>
#define vii vector<pair<int,int>>
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pdd pair<double,double>
#define vdd vector<pdd>
#define speed ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
////////////////////Only Clear Code//////////////////////////
void usaco_problem(){
freopen("milkvisits.in", "r", stdin);
freopen("milkvisits.out", "w", stdout);
}
void init(){
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif // ONLINE_JUDGE
}
const int mx = 2e5+5;
const int LOG = 25;
const ll inf = 1e18;
const ll mod = 1e8;
int n;
int st[mx][LOG], st1[mx][LOG];
int lg[mx];
int r[mx], l[mx];
void pre_log(int n){
lg[1] = 0;
for(int i = 2; i <= n;i++){
lg[i] = lg[i/2]+1;
}
}
void build(){
for(int i = 0; i < n;i++){
st[i][0] = r[i];
}
for(int j = 1;j < LOG;j++){
for(int i = 0; i < n;i++){
int pos = i + (1 << (j-1));
if(pos >= n)continue;
st[i][j] = max(st[i][j-1], st[pos][j-1]);
}
}
}
int max_query(int a, int b){
int sz = b-a+1;
int k = lg[sz];
return max(st[a][k], st[b-(1<<k)+1][k]);
}
void run_case(){
pre_log(mx-1);
cin >> n;
for(int i = 0; i < n;i++){
cin >> l[i] >> r[i];
l[i]--;r[i]--;
}
build();
int q;cin >> q;
int a;cin >> a;
int x = 0, y = r[0];
int ans = 1;
while(y != n-1){
int nxt = max_query(x, y);
//cout << x << " " << y << " " << nxt << endl;
if(nxt != y) y = nxt, ans++;
else{
cout << -1 << endl;
return;
}
}
cout << ans << endl;
}
int main(){
speed;
int t;
//cin >> t;
t = 1;
while(t--){
run_case();
}
}
/*
NEVER GIVE UP!
DOING SMTHNG IS BETTER THAN DOING NTHNG!!!
Your Guide when stuck:
- Continue keyword only after reading the whole input
- Don't use memset with testcases
- Check for corner cases(n=1, n=0)
- Check where you declare n(Be careful of declaring it globally and in main)
*/
Compilation message
passport.cpp: In function 'void usaco_problem()':
passport.cpp:32:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
32 | freopen("milkvisits.in", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
passport.cpp:33:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
33 | freopen("milkvisits.out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
passport.cpp: In function 'void init()':
passport.cpp:39:8: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
39 | freopen("input.txt", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
passport.cpp:41:8: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
41 | freopen("output.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
1108 KB |
Output is correct |
2 |
Correct |
1 ms |
1120 KB |
Output is correct |
3 |
Correct |
1 ms |
1116 KB |
Output is correct |
4 |
Correct |
51 ms |
24268 KB |
Output is correct |
5 |
Correct |
54 ms |
24520 KB |
Output is correct |
6 |
Correct |
54 ms |
24684 KB |
Output is correct |
7 |
Correct |
48 ms |
23376 KB |
Output is correct |
8 |
Correct |
35 ms |
19276 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
1108 KB |
Output is correct |
2 |
Incorrect |
1 ms |
1108 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
1108 KB |
Output is correct |
2 |
Incorrect |
1 ms |
1108 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
1108 KB |
Output is correct |
2 |
Incorrect |
1 ms |
1108 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
1108 KB |
Output is correct |
2 |
Correct |
1 ms |
1120 KB |
Output is correct |
3 |
Correct |
1 ms |
1116 KB |
Output is correct |
4 |
Correct |
51 ms |
24268 KB |
Output is correct |
5 |
Correct |
54 ms |
24520 KB |
Output is correct |
6 |
Correct |
54 ms |
24684 KB |
Output is correct |
7 |
Correct |
48 ms |
23376 KB |
Output is correct |
8 |
Correct |
35 ms |
19276 KB |
Output is correct |
9 |
Correct |
1 ms |
1108 KB |
Output is correct |
10 |
Incorrect |
1 ms |
1108 KB |
Output isn't correct |
11 |
Halted |
0 ms |
0 KB |
- |