#include<stdio.h>

#define dim 1011
struct centrala
{
    int e,c;
} a[dim];
int best[dim][dim] , best2[dim][dim];
int n,m;

void read()
{
    scanf("%d%d",&n,&m);
    for(int i=1 ;i<=n;i++)
    scanf("%d%d",&a[i].e  , &a[i].c);
}
void afis ( int a[dim][dim])
{
    for(int i=1 ;i<=n;i++,printf("\n"))
    for(int k=1 ;k<=n;k++)
    printf("%d " ,a[i][k]);
    printf("\n");
}
void solve()
{
    int max=1000000;
    for(int i=1 ;i<=n;i++)
    for(int k=i ;k<=n;k++)
    {
        best [i][k] = best[i][k-1] + a[k].e;
        
        best2[i][k]= best[i][k-1] + a[i].c;
        if ( best2[i][k] < max && best2[i][k]  >m)
        max = best2[i][k];
    }
    printf("%d\n",max);
    // afis ( best);
    // afis( best2);
}
int main ()
{
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    read();
    solve();
    return 0;
}