#include<bits/stdc++.h>
#define oo 0x3f3f3f3f

using namespace std;

const int nmax = 1e3 + 5;
const int mmax = 1e5 + 5;

int val[nmax], cost[nmax];
int T[nmax][mmax];

int main()
{
    int n, w;

    FILE *in = fopen("energii.in", "r");
    FILE *out = fopen("energii.out", "w");

    //read
    fscanf(in, "%d%d", &n, &w);
    for(int i = 1; i <= n; i++)
        fscanf(in, "%d%d", &cost[i], &val[i]);

    //bordam
    for(int i = 0; i <= n; i++)
        for(int j = 1; j <= w; j++)
            T[i][j] = oo;

    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= w; j ++)
            {
                if( cost[i] > j)
                    T[i][j] = min(T[i-1][j], val[i]);
                else T[i][j] = min(T[i-1][j], T[i-1][j - cost[i]]);
            }
    }
    /*
    for(int i = 1; i <= n; i++){
        for(int j = 0; j <= w; j++)
            fprintf(out, "%d ", T[i][j]);
        fprintf(out, "\n");
    } */

    int s = T[n][w];
    if( s >= w)
        fprintf(out, "%d", s);
    else fprintf(out,"%d", -1);
    return 0;
}