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

unsigned g,w,eg[1001],cg[1001],i;
float ran[1001];

void vectori(unsigned g)
    {
        for( i=0;i<g;i++)
            {
                fin>>eg[i];
                fin>>cg[i];
                ran[i]=(float)cg[i]/eg[i];
            }
    }

int ok(unsigned g)
    {
        unsigned oki=0;
        for (i=0;i<g;i++)
             if(eg[i]!=0)
                    oki=1;
        return oki;
    }


int main()
{
    fin>>g>>w;
    vectori(g);
    if(ok(g)==0)
            //...
    //else
        fout<<"-1";
    return 0;
}