1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#ifdef LOCAL
#include "../debug/debug.h"
#else
#define debug(...)
#define debugArr(...)
#endif

using namespace std;
using namespace __gnu_pbds;

using ll = long long;
using db = long double;
using pi = pair<int,int>;
using pl = pair<ll,ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vb = vector<bool>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vvi = vector<vi>;

#define mp make_pair
#define eb emplace_back
#define pb push_back
#define x first
#define y second
#define sz(x) int((x).size())
#define bg(x) begin(x)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(), (x).rend() 
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define per(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define ft front()
#define bk back()
#define rsz resize
#define ins insert
#define each(a,x) for(auto&a:x)

template<class T> bool ckmin(T& a, T b) { return b<a?a=b,1:0; }
template<class T> bool ckmax(T& a, T b) { return b>a?a=b,1:0; }
template<class T> int lwb(vector<T>& a, const T& b) { return int(lower_bound(all(a),b)-bg(a)); }
template<class T> int upb(vector<T>& a, const T& b) { return int(upper_bound(all(a),b)-bg(a)); }
template<class T> void remdup(vector<T>& v) { sort(all(v)); v.erase(unique(all(v)),end(v)); }

constexpr int pct(int x) { return __builtin_popcount(x); }
constexpr int bitlog(int x) { return x == 0 ? 0 : 31 - __builtin_clz(x); }
constexpr int pct(ll x) { return __builtin_popcountll(x); }
constexpr int bitlog(ll x) { return x == 0 ? 0 : 63 - __builtin_clzll(x); }

constexpr ll cdiv(ll a, ll b) { return a / b + ((a ^ b) > 0 && a % b); }  // divide a by b rounded up
constexpr ll fdiv(ll a, ll b) { return a / b - ((a ^ b) < 0 && a % b); }  // divide a by b rounded down
constexpr int cdiv(int a, int b) { return a / b + ((a ^ b) > 0 && a % b); }  // divide a by b rounded down
constexpr int fdiv(int a, int b) { return a / b - ((a ^ b) < 0 && a % b); }  // divide a by b rounded down

const pi MOVES[] = {{-1, 0}, {0, -1}, {1, 0}, {0, 1}};

#ifdef LOCAL
mt19937_64 rng(0xabadbeef);
#else
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
#endif

ll randr(ll l, ll r) { return uniform_int_distribution<ll>(l, r)(rng); }

const int N = 5e5+8;
ll dp[N];
int a[N], w[N];
int n, c;
pair<ll, int> best[N][2];
ll best_by_color[N];
int idx_by_color[N];

void fix(int idx) {
    if (best[idx][0].x < best[idx][1].x) {
        swap(best[idx][0], best[idx][1]);
    }
}

void upd(int idx, ll hei, int col) {
    rep(i,0,2) {
        if (best[idx][i].y == col) {
            ckmax(best[idx][i].x, hei);
            fix(idx);
            return;
        }
    }

    if (best[idx][1].x < hei) {
        best[idx][1].x = hei;
        best[idx][1].y = col;
        fix(idx);
    }
}

void prop(int idx) {
    rep(i,0,2) {
        upd(idx + 1, best[idx][i].x, best[idx][i].y);
    }
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);

    cin >> n >> c;
    rep(i,0,n) {
        cin >> a[i] >> w[i];
    }

    rep(i,0,N) best[i][0] = best[i][1] = mp(-1, -1);

    int prv_idx = 0;

    rep(i,0,n) {
        while (prv_idx < a[i]) {
            prop(prv_idx++);
        }

        if (idx_by_color[w[i]] == a[i]) continue;

        debug(i, a[i], best[a[i] - 1][0], best[a[i] - 1][1]);

        rep(j,0,2) {
            auto [hei, col] = best[a[i] - 1][j];
            if (col == -1) continue;
            if (col != w[i]) {
                ckmax(dp[i], hei - c);
            }
            else {
                ckmax(dp[i], hei);
            }
        }

        ckmax(dp[i], best_by_color[w[i]]);

        dp[i] += a[i];

        upd(a[i], dp[i], w[i]);

        idx_by_color[w[i]] = a[i];
        ckmax(best_by_color[w[i]], dp[i]);
    }

    ll res = 0;
    rep(i,0,n) ckmax(res, dp[i]);
    cout << res << '\n';

    return 0;
}