//#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <set>
#include <algorithm>
#include <bitset>
#include <time.h>
#include <tuple>
#include <fstream>
#include <iomanip>
#include <utility>

#pragma warning "da 100% din tine. :)"
#define nl '\n'
#define cnl cout << '\n';
#define sp ' '
#define pb(x) push_back(x)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define ll long long
#define ull unsigned ll
#ifdef INFOARENA
#define ProblemName "energii"
#endif
#define MCONCAT(A, B) A B
#ifdef ProblemName
#define InFile MCONCAT(ProblemName, ".in")
#define OuFile MCONCAT(ProblemName, ".out")
#else
#define InFile "a.in"
#define OuFile "a.out"
#endif

using namespace std;
ifstream cin(InFile);
ofstream cout(OuFile);

template<class v, class type>
void print(v Vector, type nr) {
    for_each(all(Vector), [](type x) {
        cout << x << ' ';
    });
}

void nimic() {
    return;
}

int val[1001];
int dp[5001];
int cost[1001];

int main() {
    ios_base::sync_with_stdio(false);
    clock_t tStart = clock();
    int W, n;
    cin >> n >> W;
    for (int i = 0; i < n; ++i)
        cin >> cost[i] >> val[i];
    for(int i = 1;i<=W;++i)
        dp[i] = 1999999999;
    for (int i = 0; i < n; ++i)
        for (int j = W; j >= 1; --j) {
            if (j <= cost[i]) {
                dp[j] = min(dp[j], val[i]);
            } else
                dp[j] = min(dp[j], dp[j - cost[i]] + val[i]);
        }
    cout << dp[W];


    printf("\nTime taken: %.2fs\n", (double) (clock() - tStart) / CLOCKS_PER_SEC);
}