// need
#include <iostream>
#include <algorithm>

// data structure
#include <bitset>
//#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <array>
//#include <tuple>
//#include <unordered_map>
#include <unordered_set>
#include <complex>
//#include <deque>
#include<valarray>

// stream
//#include <istream>
//#include <sstream>
//#include <ostream>
//#include <fstream>

// etc
#include <cmath>
#include <cassert>
#include <functional>
#include <iomanip>
//#include <typeinfo>
#include <chrono>
#include <random>
#include <numeric>

// input
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, ...)type __VA_ARGS__;MACRO_VAR_Scan(__VA_ARGS__);
template<typename T> void MACRO_VAR_Scan(T& t) { std::cin >> t; }
template<typename First, typename...Rest>void MACRO_VAR_Scan(First& first, Rest&...rest) { std::cin >> first; MACRO_VAR_Scan(rest...); }
#define VEC_ROW(type, n, ...)std::vector<type> __VA_ARGS__;MACRO_VEC_ROW_Init(n, __VA_ARGS__); for(int i=0; i<n; ++i){MACRO_VEC_ROW_Scan(i, __VA_ARGS__);}
template<typename T> void MACRO_VEC_ROW_Init(int n, T& t) { t.resize(n); }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Init(int n, First& first, Rest&...rest) { first.resize(n); MACRO_VEC_ROW_Init(n, rest...); }
template<typename T> void MACRO_VEC_ROW_Scan(int p, T& t) { std::cin >> t[p]; }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Scan(int p, First& first, Rest&...rest) { std::cin >> first[p]; MACRO_VEC_ROW_Scan(p, rest...); }
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;

// output
#define OUT(d) std::cout<<d;
#define FOUT(n, d) std::cout<<std::fixed<<std::setprecision(n)<<d;
#define SOUT(n, c, d) std::cout<<std::setw(n)<<std::setfill(c)<<d;
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define SPBR(i, n) std::cout<<(i + 1 == n ? '\n' : ' ');
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define SHOW(d) {std::cerr << #d << "\t:" << d << "\n";}
#define SHOWVECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOWVECTOR2(v) {std::cerr << #v << "\t:\n";for(const auto& xxx : v){for(const auto& yyy : xxx){std::cerr << yyy << " ";}std::cerr << "\n";}}
#define SHOWQUEUE(a) {auto tmp(a);std::cerr << #a << "\t:";while(!tmp.empty()){std::cerr << tmp.front() << " ";tmp.pop();}std::cerr << "\n";}

// utility
#define ALL(a) (a).begin(),(a).end()
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RFOR(i, a, b) for(int i=(b)-1;i>=(a);--i)
#define REP(i, n) for(int i=0;i<int(n);++i)
#define RREP(i, n) for(int i=int(n)-1;i>=0;--i)
#define FORLL(i, a, b) for(ll i=ll(a);i<ll(b);++i)
#define RFORLL(i, a, b) for(ll i=ll(b)-1;i>=ll(a);--i)
#define REPLL(i, n) for(ll i=0;i<ll(n);++i)
#define RREPLL(i, n) for(ll i=ll(n)-1;i>=0;--i)
#define IN(a, x, b) (a<=x && x<b)
template<typename T> inline T CHMAX(T& a, const T b) { return a = (a < b) ? b : a; }
template<typename T> inline T CHMIN(T& a, const T b) { return a = (a > b) ? b : a; }
#define EXCEPTION(msg) throw std::string("Exception : " msg " [ in ") + __func__ + " : " + std::to_string(__LINE__) + " lines ]"
#define TRY(cond, msg) try {if (cond) EXCEPTION(msg);}catch (std::string s) {std::cerr << s << std::endl;}
void CHECKTIME(std::function<void()> f) { auto start = std::chrono::system_clock::now(); f(); auto end = std::chrono::system_clock::now(); auto res = std::chrono::duration_cast<std::chrono::nanoseconds>((end - start)).count(); std::cerr << "[Time:" << res << "ns  (" << res / (1.0e9) << "s)]\n"; }

// test
template<class T> std::vector<std::vector<T>> VV(int n) {
	return std::vector<std::vector<T>>(n);
}
template<class T> std::vector<std::vector<T>> VV(int n, int m, T init = T()) {
	return std::vector<std::vector<T>>(n, std::vector<T>(m, init));
}
template<typename S, typename T>
std::ostream& operator<<(std::ostream& os, std::pair<S, T> p) {
	os << "(" << p.first << ", " << p.second << ")"; return os;
}

// type/const

#define int ll
using ll = long long;
using ull = unsigned long long;
using PAIR = std::pair<int, int>;
using PAIRLL = std::pair<ll, ll>;
constexpr int INFINT = 1 << 30;                          // 1.07x10^ 9
constexpr int INFINT_LIM = (1LL << 31) - 1;              // 2.15x10^ 9
constexpr ll INFLL = 1LL << 60;                          // 1.15x10^18
constexpr ll INFLL_LIM = (1LL << 62) - 1 + (1LL << 62);  // 9.22x10^18
constexpr double EPS = 1e-7;
constexpr int MOD = 1000000007;
constexpr double PI = 3.141592653589793238462643383279;

//SegmentTree(?????°??¨)
template <class T>
class SegmentTree {
private:
	T init_val;
	std::vector<T> ary;
	std::function<T(T, T)> func;
public:
	// ?????¨???(??????????????§??????n??¨??????)
	// SegmentTree<int> st(n,  INFLL, [](int l, int r){return std::min(l, r);}); ????°????
	// SegmentTree<int> st(n, -INFLL, [](int l, int r){return std::max(l, r);}); ?????§???
	// SegmentTree<int> st(n,    0, [](int l, int r){return l+r;});            ????¨?
	SegmentTree(int n, T val, std::function<T(T, T)> f) : init_val(val), func(f) {
		ary.resize(static_cast<int>(std::pow(2, std::ceil(std::log(n) / std::log(2)) + 1) - 1), val);
	}
	void init(int n, T val, std::function<T(T, T)> f) {
		ary.resize(static_cast<int>(std::pow(2, std::ceil(1.0*std::log(n) / std::log(2)) + 1) - 1), val);
		init_val = val;
		func = f;
	}
	void update(int i, T val) {
		i += ary.size() / 2;
		ary[i] = val;
		while (i > 0) {
			i = (i - 1) / 2;
			ary[i] = func(ary[2 * i + 1], ary[2 * i + 2]);
		}
	}
	// ??????[a, b)???func????????????????????? (query_(a, b, 0, 0, n)??¨????????????)
	T query_(int a, int b, int i, int l, int r) {
		if (r <= a || b <= l) return init_val;
		if (a <= l && r <= b) return ary[i];
		else {
			T vl = query_(a, b, 2 * i + 1, l, (l + r) / 2);
			T vr = query_(a, b, 2 * i + 2, (l + r) / 2, r);
			return func(vl, vr);
		}
	}
	// ??????(b)????°??????§?????????????????????
	T query(int a, int b) {
		return query_(a, b, 0, 0, ary.size() / 2 + 1);
	}

	T operator[](int i) {
		return query(i, i + 1);
	}
};

int calcSum(int a, int d, int n) {
	return n * (2 * a + (n - 1) * d) / 2;
}

int calc(int a, int d, int i, int j) {
	return calcSum(a, d, j) - calcSum(a, d, i);
}

//#define DEBUG

signed main() {
	INIT;
#ifdef DEBUG
	while (true) {
		std::random_device rnd;
		std::mt19937 mt(rnd());
		std::uniform_int_distribution<> rand(/* min */1, /* max */10);
		std::uniform_int_distribution<> randA(/* min */0, /* max */100000);
		std::uniform_int_distribution<> randD(/* min */1, /* max */1000);
		int n = rand(mt);
		int l = rand(mt);
		int k = rand(mt) * rand(mt);
		if (k > n*l) continue;
		if (n*l*k > 20000000) continue;
		n += 4;
		std::vector<int> a(n, 0), d(n, 0);
		FOR(i, 2, n - 2) {
			a[i] = randA(mt);
			d[i] = randD(mt);
		}
#else
	int cntcntcnt = 0;
	while (cntcntcnt++ == 0) {
		VAR(int, n, l, k);
		n += 4;
		std::vector<int> a(n, 0), d(n, 0);
		FOR(i, 2, n - 2) {
			std::cin >> a[i] >> d[i];
		}
#endif

		int ka = k / l;
		int ha = k % l;
		if (ka > 0) {
			--ka;
			ha += l;
		}

		SegmentTree<int> st(n, 0, [](int l, int r) {return l + r; });
		REP(i, n) {
			int t = calc(a[i], d[i], 0, l);
			st.update(i, t);
		}

		int ans = 0;
		REP(L, n) {
			int R = L + ka + 1;
			if (R >= n) break;
			int sum = st.query(L + 1, R);

			int LL = std::max(ha - l, 0LL), RR = l + 1;
			int a1 = a[L], d1 = d[L], a2 = a[R], d2 = d[R];
			auto f = [&](int i) {
				int t;
				if (i >= ha) {
					t = calc(a2, d2, i - ha, i);
				}
				else {
					t = calc(a1, d1, l - ha + i, l) + calc(a2, d2, std::max(0LL, i - ha), i);
				}
				return t;
			};
			int cnt = 0;
			while (cnt++ < 200) {
				int m1 = (LL + LL + RR) / 3;
				int m2 = (LL + RR + RR) / 3;
				if (f(m1) < f(m2)) LL = m1;
				else RR = m2;
			}
			int di = 50;
			LL -= di;
			CHMAX(LL, std::max(ha - l, 0LL));
			RR += di;
			CHMIN(RR, l + 1);
			FOR(i, LL, RR) {
				CHMAX(ans, sum + f(i));
			}
		}
		///////////////////////////////
		// pre 
		ka = k / l;
		ha = k % l;

		REP(L, n) {
			int R = L + ka + 1;
			if (R >= n) break;
			int sum = st.query(L + 1, R);

			int LL = 0, RR = ha + 1;
			int ma = 0;
			auto f = [&](int a1, int d1, int a2, int d2, int i) {
				int t = (ha - i)*(2 * a1 + (2 * l - ha + i - 1)*d1) / 2 + i*(2 * a2 + (i - 1)*d2) / 2;
				return t;
			};
			int cnt = 0;
			while (cnt++ < 50) {
				int m1 = (LL + LL + RR) / 3;
				int m2 = (LL + RR + RR) / 3;
				if (f(a[L], d[L], a[R], d[R], m1) < f(a[L], d[L], a[R], d[R], m2)) LL = m1;
				else RR = m2;
			}
			int di = 50;
			LL -= di;
			CHMAX(LL, 0LL);
			RR += di;
			CHMIN(RR, ha + 1);
			FOR(i, LL, RR) {
				CHMAX(ma, f(a[L], d[L], a[R], d[R], i));
			}
			CHMAX(ans, sum + ma);
		}

		///////////////////////////////
		OUT(ans)BR;
#ifdef DEBUG
		std::vector<int> b(n*l, 0);
		REP(i, n) {
			b[i*l] = a[i];
			FOR(j, 1, l) {
				b[i*l + j] = b[i*l + j - 1] + d[i];
			}
		}
		int ans2 = 0;
		REP(i, n*l) {
			if (i + k > n*l) break;
			int sum = 0;
			FOR(j, i, i + k) sum += b[j];
			CHMAX(ans2, sum);
		}
		if (ans != ans2) {
			OUT("===========")BR;
			OUT(n - 4)SP OUT(l)SP OUT(k)BR;
			FOR(i, 2, n - 2) {
				OUT(a[i])SP OUT(d[i])BR;
			}
			OUT("===========")BR;
			SHOWVECTOR(b);
			OUT(ans)SP OUT(ans2)BR;
			return 0;
		}
		FLUSH;
#endif
	}
	return 0;
}

Measured memory_bytes: 6728