#include <bits/stdc++.h>
#include <cassert>
using namespace std;
mt19937 timmy_loves_gambling(73);
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define readv(v) do { for(auto &i: v) cin >> i; } while(0)
#define _ << " " <<
#define lf "\n"
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<long long, long long>
#define fi first
#define se second
template<typename... Args>
using vec = vector<Args...>;
#ifndef MARCO
bool dbg = 0;
#define infor(str, ...)
#define infof(str, ...)
#else
bool dbg = 1;
#define infor(str, ...) do { print(stderr, str, ##__VA_ARGS__); } while(0)
#define infof(str, ...) do { println(stderr, str, ##__VA_ARGS__); } while(0)
#endif
signed main() {
ios::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int N; ll M;
cin >> N >> M;
vec<pll> V(N);
for(auto &[v, w]: V) {
cin >> v >> w;
}
sort(all(V), [&](pll i, pll j){
if(i.se != j.se) return i.se < j.se;
return i.fi > j.fi;
});
vec<vec<ll>> S;
vec<ll> W;
ll pw = -1;
for(int i = 0; i < N; i++) {
auto &[v, w] = V[i];
if(pw == w) S.back().emplace_back(v);
else {
if(pw != -1) W.push_back(pw);
S.push_back({v});
pw = w;
}
}
W.push_back(pw);
M = M/W[0] * W[0];
ll ans = 0;
for(int i = 1; i < W.size(); i++) {
for(int j=0; j<M%W[i]/W[i-1]; j++)
ans += S[i-1][j];
vec<ll> Sn;
ll v = 0;
int p = 0;
ll d = 0;
for(int j=M%W[i]/W[i-1]; j<S[i-1].size(); j++) {
v += S[i-1][j];
d++;
if(d == W[i]/W[i-1]) {
while(p < S[i].size() && S[i][p] > v)
Sn.push_back(S[i][p++]);
Sn.push_back(v);
v = 0;
d = 0;
}
}
while(p < S[i].size())
Sn.push_back(S[i][p++]);
S[i].swap(Sn);
M = M/W[i] * W[i];
}
for(int j=0; j<min(M/W.back(), (ll)S.back().size()); j++)
ans += S.back()[j];
cout << ans << lf;
}
