#include <fstream>
using namespace std;
ifstream r("energii.in");
ofstream w("energii.out");

unsigned e,c,n,x,v1[1001][1001];
//float v[1001];

void vec(unsigned n)
    {
        for(unsigned i=0;i<n;i++)
            {
                r>>e>>c;
                v1[i][0]=e;
                v1[i][1]=c;
                //v[i]=(float)c/e;
            }

    }



void minim(unsigned n)
    {
            for(unsigned i=0;i<n;i++)
                {
                    unsigned a=v1[i][1],b=v1[i][0];
                    while(v1[i][0]<x)
                        {
                            v1[i][0]+=b;
                            v1[i][1]+=a;
                        }
                }
            unsigned m=v1[0][1];
            for(unsigned i=1;i<n;i++)
                {
                    if(v1[i][1]<m)
                        m=v1[i][1];
                }
            w<<m;

        //float m=v[0];
        //unsigned f=0;
        /*for(unsigned i=1;i<n;i++)
                if(v[i]<m)
                   {
                       m=v[i];
                       f=i;
                   }
        unsigned a=v1[f][1],b=v1[f][0];
        while(v1[f][0]<x)
            {
                v1[f][1]+=a;
                v1[f][0]+=b;
            }
        w<<v1[f][1];*/

    }

int main()
{
    r>>n>>x;
    vec(n);
    minim(n);
    //for(unsigned i=0;i<n;i++) vector
      //  w<<v[i]<<" ";
    //for(unsigned i=0;i<n;i++) matrice
      //      w<<v1[i][0]<<" "<<v1[i][1]<<"\n";
    return 0;
}