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
#include <bits/stdc++.h>
using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef double db;

const int W = 1 << 19;
const LL LINF = 1e18;

template<typename T>
void updMax(T& a, T b)
{
	a = max(a, b);
}

vector<PII> vec[W];

int main()
{
	ios::sync_with_stdio(0); 
	cin.tie(0);
	int n, c;
	cin >> n >> c;
	VI a(n), w(n);
	FOR(i, 0, n)
	{
		cin >> a[i] >> w[i];
		vec[w[i]].PB({a[i], i});
	}
	VI nxt(n), nxtSameW(n);
	FOR(i, 0, n)
	{
		nxt[i] = upper_bound(ALL(a), a[i]) - a.begin();
		int j = upper_bound(ALL(vec[w[i]]), MP(a[i], n)) - vec[w[i]].begin();
		nxtSameW[i] = j == SZ(vec[w[i]]) ? n : vec[w[i]][j].S;
	}
	// dp0[i] -- can take i-th
	// dp1[i] -- took i-th
	VL dp0(n + 1, -LINF), dp1(n + 1, -LINF);
	dp0[0] = 0;
	FOR(i, 0, n)
	{
		updMax(dp1[i], dp0[i] + a[i]);
		updMax(dp0[i + 1], dp0[i]);
		updMax(dp1[nxtSameW[i]], dp1[i] + a[nxtSameW[i]]);
		updMax(dp0[nxt[i]], dp1[i] - c);
	}
	cout << *max_element(dp1.begin(), dp1.begin() + n) << "\n";
	return 0;
}