#include <fstream>
using namespace std;

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

const int N=1005;

int n, vgoal, v[N], g[N], dp[N];

int main()
{
    fin>>n>>vgoal;
    int gmax=0;
    for(int i=1;i<=n;++i)
        fin>>v[i]>>g[i], gmax+=g[i];

    for(int i=1;i<=n;++i)
        for(int j=gmax;j>=g[i];--j)
            dp[j]=max(dp[j], dp[j-g[i]]+v[i]);
    int ans=0;
    for(int i=0;i<=gmax;++i)
        if(dp[i]>=vgoal)
        {
            fout<<i;
            return 0;
        }
    fout<<-1;
    return 0;
}