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

// template {{{
#define  range(i, l, r) for (int i = (int)(l); i < (int)(r); (i) += 1)
#define rrange(i, l, r) for (int i = (int)(r) - 1; i >= (int)(l); (i) -= 1)

#define  whole(f, x, ...) ([&](decltype((x)) container) { return (f)(  begin(container),  end(container), ## __VA_ARGS__); })(x)
#define rwhole(f, x, ...) ([&](decltype((x)) container) { return (f)( rbegin(container), rend(container), ## __VA_ARGS__); })(x)

#define debug(x) cerr << "(" << __LINE__ << ")" << #x << ": " << (x) << endl

using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;

// constexpr i32 mod   = 998244353;
constexpr i32 mod   = 1e9 + 7;
constexpr i32 inf   = 1001001001;
constexpr i64 infll = 1001001001001001001ll;

constexpr int dx[] = {0, -1, 1, 0, -1, 1, -1, 1};
constexpr int dy[] = {-1, 0, 0, 1, -1, -1, 1, 1};

struct IoSetup { IoSetup(int x = 15){ cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(x); cerr << fixed << setprecision(x); } } iosetup;

template <typename T = i64> T input() { T x; cin >> x; return x; }

template <typename T> ostream &operator<<(ostream &os, vector<T> &v) { range(i, 0, v.size()) { os << v[i] << (i + 1 != v.size() ? " " : ""); } return os; }
template <typename T> istream &operator>>(istream &is, vector<T> &v) { for (T &in : v) is >> in; return is; }

template <typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
template <typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { is >> p.first >> p.second; return is; }

template <typename T> vector<T> make_vector(size_t a, T b) { return vector<T>(a, b); }
template <typename... Ts> auto make_vector(size_t a, Ts... ts) { return vector<decltype(make_vector(ts...))>(a, make_vector(ts...)); }

template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
// }}}

void solver() {
    int n, x;
    cin >> n >> x;

    vector< int > ds(n), cs(n);
    range(i, 0, n) {
        cin >> ds[i] >> cs[i];
    }

    vector< int > dist(101010 * 5, inf);
    int s = 101010 * 3;
    int g = 101010 * 3 + x;

    using pii = pair< int, int >;
    priority_queue<pii, vector<pii>, greater<pii>> pq;
    pq.emplace(0, s);
    dist[s] = 0;

    while (!pq.empty()) {
        pii p = pq.top();
        pq.pop();

        int v = p.second;
        if (dist[v] < p.first) continue;

        range(i, 0, n) {
            int u = v + ds[i];
            if (u < 0 || dist.size() <= u) continue;
            if (dist[u] > dist[v] + cs[i]) {
                dist[u] = dist[v] + cs[i];
                pq.emplace(dist[u], u);
            }

            u = v - ds[i];
            if (u < 0 || dist.size() <= u) continue;
            if (dist[u] > dist[v] + cs[i]) {
                dist[u] = dist[v] + cs[i];
                pq.emplace(dist[u], u);
            }
        }
    }


    if (dist[g] == inf) {
        cout << -1 << endl;
    } else {
        cout << dist[g] << endl;
    }
}

signed main(int argc, char *argv[]) {
    solver();
}



Measured memory_bytes: 8968