#include <iostream>
#include <cstdio>
#define NMAX 1001
#define WMAX 5020
#define inf 2000000000
using namespace std;

int N,W;
int costuri[NMAX];
int puteri[NMAX];
int dp[WMAX];
int rez = inf;

void citire()
{
    scanf("%d%d",&N,&W);
    for(int i=1;i<=N;i++)
        scanf("%d%d",&costuri[i],&puteri[i]);
}

void rezolvare()
{
    for(int i=costuri[1];i<=WMAX;i++)
        dp[i] = puteri[1];

    for(int i=2;i<=N;i++)
        for(int j=WMAX;j>=puteri[i];j--)
            if(dp[j]<puteri[i] + dp[j-costuri[i]])
                    dp[j] = puteri[i] + dp[j-costuri[i]];

    for(int i=1;i<WMAX;i++)
        if(rez>dp[i] && dp[i]>=W)
            rez=dp[i];


    if(rez == inf)
        cout<<-1;
    else
        cout<<rez;
}

int main()
{
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    citire();
    rezolvare();
    return 0;
}