s,p,q,x,y;main(f){for(scanf("%d%d%*d",&p,&q),s=p,f=q;p|q?x=s:0;f=x)s=f%x;for(;~scanf("%d%d",&x,&y);s+=f?!(x%f|y%f|(x+y)/f%(p/f%2*q/f%2+1)):!x&!y);s=!printf("%d",s);}