J=lambda:map(int,input().split())
H=[0]*4
for i in range(sum(J())):
	A,B=J();v=0
	while(A&1<1)*(v<3):A>>=1;v+=1
	H[v]+=B
print(H[3]+[(H[1]+2*H[2])//3,(H[2]+H[1])>>1][H[1]<H[2]])