#include <iostream>
#include <fstream>

using namespace std;

#define INF 0x3f3f3f3f

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

int n, G, dp[10005], w[5005], p[5005];

int main()
{
    fin >> n >> G;
    for(int i = 1; i <= n; i++)
        fin >> w[i] >> p[i];
    for(int i = 1; i <= 10001; i++)
        dp[i] =  10000000;
    dp[0] = 0;
    for(int i = 1; i <= n; ++i)
        for(int j = 10001; j >= w[i]; --j)
            dp[j] = min(dp[j], dp[j - w[i]] + p[i]);
    int ans = 10000000;
    for(int i = G; i <= 10001; ++i)
        ans = min(ans, dp[i]);
    if(ans == 10000000)
        fout << "-1";
    else fout << ans;

    return 0;
}