Problem:
Score : 600 points

Problem Statement

There is a grid of squares with H+1 horizontal rows and W vertical columns.

You will start at one of the squares in the top row and repeat moving one square right or down. However, for each integer i from 1 through H, you cannot move down from the A_i-th, (A_i + 1)-th, \ldots, B_i-th squares from the left in the i-th row from the top.

For each integer k from 1 through H, find the minimum number of moves needed to reach one of the squares in the (k+1)-th row from the top. (The starting square can be chosen individually for each case.) If, starting from any square in the top row, none of the squares in the (k+1)-th row can be reached, print -1 instead.

Constraints

1 \leq H,W \leq 2\times 10^5

1 \leq A_i \leq B_i \leq W

Input

Input is given from Standard Input in the following format:

H W
A_1 B_1
A_2 B_2
:
A_H B_H

Output

Print H lines. The i-th line should contain the answer for the case k=i.

Sample Input 1

4 4
2 4
1 1
2 3
2 4

Sample Output 1

1
3
6
-1

Let (i,j) denote the square at the i-th row from the top and j-th column from the left.

For k=1, we need one move such as (1,1) → (2,1).

For k=2, we need three moves such as (1,1) → (2,1) → (2,2) → (3,2).

For k=3, we need six moves such as (1,1) → (2,1) → (2,2) → (3,2) → (3,3) → (3,4) → (4,4).

For k=4, it is impossible to reach any square in the fifth row from the top.

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>

#define IOS ios :: sync_with_stdio(false); cin.tie(0); cout.tie(0)
#define AfterDecimal(n) cout << fixed << setprecision(n);
#define ll long long int
#define ld long double
#define all(a) a.begin(), a.end()
#define pii pair<int, int>
#define pll pair<ll, ll>
#define bits(x) __builtin_popcount(x)

using namespace __gnu_pbds;
using namespace std;

// #pragma GCC optimize("Ofast")
// #pragma GCC target("avx,avx2,fma")
// #pragma GCC optimization ("unroll-loops")

//template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef tree<int, null_type, less<int>, rb_tree_tag,
            tree_order_statistics_node_update>
    ordered_set;

#ifdef LOCAL
#define debug(...) __f(#__VA_ARGS__, __VA_ARGS__)
template<typename Arg1>
void __f(const char* name, Arg1&& arg1){
    cout << "# "<< name << " = " << arg1 << '\n';
}
template<typename Arg1, typename... Args>
void __f(const char* names, Arg1 && arg1, Args &&... args){
        const char* comma = strchr(names + 1 ,',');
        cout << "# ";
        cout.write(names, comma - names)<< " = " << arg1 << " | ";
        __f(comma + 1, args...);
}
#else
#define debug(...) 36
#endif


std::mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
inline int ri(int a, int b) {
    return uniform_int_distribution<int>(a, b)(rng);
}

ll power(ll x, ll y, ll p){
   ll res = 1;
   x = x % p;
   while (y > 0) {
      if (y & 1)
         res = (res * x) % p;
      y = y >> 1;
      x = (x * x) % p;
   }
   return res;
}

const ll INF = (ll)(8e18);
const ll MOD = (ll)(1e9 + 7);
const ll HMOD = (ll)4222234727;
const ll Hashprime = (ll)31;

const int maxn = 100100;

int32_t main(){
    IOS;
    #ifndef ONLINE_JUDGE
    //  freopen("input.txt", "r", stdin);
    //  freopen("output.txt", "w", stdout);
    #endif
    int t = 1; // cin >> t;
    while(t--){
      int h,w; cin >> h >> w;
      int ans = 0;
      int prev = 1;
      for(int i = 1; i <= h; i++){
         int l,r; cin >> l >> r;
         if(ans == -1){
            cout << ans << '\n';
            continue;
         }
         if(prev <= r && prev >= l){
             ans += (r - prev + 1);
             prev = r + 1;
             if(prev > w) ans = -1;
         }
         if(ans != -1) ans += 1;
         cout << ans << '\n';
      }
    }
    #ifdef LOCAL
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
    #endif
}
//g++ -DLOCAL -std=c++17 -Wshadow -Wall -o "c" "comp.cpp" -fsanitize=address -fsanitize=undefined -D_GLIBCXX_DEBUG -g