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
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<pii> vpii;
typedef vector<string> vs;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef long double ld;
typedef unordered_map<int, int> umii;
typedef vector<pair<ll,ll>> vpll;
typedef tuple<int,int,int> tp;
typedef unsigned long long ull;
const ll MOD = 1e9+696969;

const ll neg = -LLONG_MAX;
struct blck
{
    int a, w;
};

void solve()
{
    int n, c;
    cin >> n >> c;
    vector<blck> block(n);

    for(int i=0; i<n; ++i) cin >> block[i].a >> block[i].w;

    int mx = 500'000;
    vll bestp(mx+1, neg);

    ll global1 = neg;
    int global10=-1;
    ll global2= neg;
    ll ans=0; 
    int i=n-1;

    while(i>=0)
    {
        int cura =block[i].a;
        vpll upd;

        while(i>=0 and block[i].a == cura)
        {
            int p=block[i].w;

            ll bestopt=0;
            if(bestp[p]!=neg)
            bestopt=max(bestopt, bestp[p]);

            ll cand = (global10 != p? global1 : global2);

            if(cand!=neg)
            bestopt=max(bestopt, cand-c);

            ll dp=cura+bestopt;
            ans=max(ans, dp);
            upd.push_back({p,dp});
            i--;
        }

        for(auto& x: upd)
        {
            int pat = x.first;
            ll val = x.second;
            if(val>bestp[pat])
            bestp[pat]=val;

            if(val > global1)
            {
                if(global10 == pat)
                global1 = val;
                else
                {
                    global2=global1;
                    global1=val;
                    global10=pat;
                }
            }
            else if(pat!=global1 and val> global2)
            global2=val;
        }
    }

    cout << ans << "\n";
    
}


int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    solve();
    return 0;
}