#include<iostream>using namespace std;struct Node{ double dis,speed,need;};Node nodes[1010];int big,v;int main(){ while(scanf("%d%d",&big,&v)!=EOF){ int number; scanf("%d",&number); if(number==0){ printf("%dn",big*v); continue; } int i; double need=100000000; for(i=1;i<=number;i++){ scanf("%lf%lf",&nodes[i].dis,&nodes[i].speed); nodes[i].need=nodes[i].dis/nodes[i].speed; if(nodes[i].need<need){ need=nodes[i].need; } } if(need>big){ printf("%dn",big*v); }else{ if(need-(int)need==0){ need=(int)(need-1); if(need==0){ printf("0n"); }else{ big=(big-need)/2+need; printf("%dn",big*v); } }else{ need=(int)need; if(need==0){ printf("0n"); }else{ big=(big-need)/2+need; printf("%dn",big*v); } } } } return 0;}
