#include<bits/stdc++.h> using namespace std; int x,y,k,ai,xi,bi,yi; int main(){ cin>>x>>y>>k; if(x==y){ cout<<0; return 0; } for(int i=1;i<=k;i++){ cin>>ai>>xi>>bi>>yi; x+=ai*xi; y+=bi*yi; if(x<0) x=0; if(y<0) y=0; if(x==y){ cout<<i<<endl; return 0; } } cout<<-1<<endl; return 0; }