#include <iostream>
using namespace std;
int main()
{
int X,Y,Q,P,A;
double Z,Min=9999999;
scanf("%d %d",&X,&Y);
Z=(double)(X*1000)/Y;
if(Z<Min)Min=Z;
scanf("%d",&A);
for(int x=0; x<A; x++)
{
scanf("%d %d",&P,&Q);
Z=(double)(P*1000)/Q;
if(Z<Min)Min=Z;
}
printf("%.2lf",Min);
}