#include <iostream>
#include <fstream>
#include <stdint.h>
#include <cctype>
#include <cstring>
#include <algorithm>
#include <vector>
#include <map>
#include <cmath>
#include <set>
#include <queue>

using namespace std;
typedef long long ll;
#pragma warning(disable : 4996)
;

ifstream fin("energii.in");
ofstream fout("energii.out");

//rucsac discret

int p[5001], w[5001], n, g, dp[10001];

int main() {

	for (int i = 1; i < 10001; i++)
		dp[i] = 100000;

	fin >> n >> g;

	for (int i = 1; i <= n; i++)
		fin >> p[i] >> w[i];
	//dp este in functie de energia produsa iar costul treb sa fie minim
	for(int i = 1; i <= n; i++)
		for (int j = g - 1; j >= 0; j--) {
			dp[j + p[i]] = min(dp[j + p[i]], dp[j] + w[i]);
		}

	int mini = 100000;
	for (int i = g; i < 10001; i++)
		mini = min(mini, dp[i]);
	if (mini == 100000) fout << -1;
	else {
		fout << mini;
	}
	return 0;
}