#define E f.addEdge
ll@N,@M,@(L,R)[N],B[5N]{};maxflow<ll,ll>f;f.malloc(M=coordcomp(N,L,N,R)+3N);f.init(M);rep(i,N)E(M-2,i,1),E(i,N+L[i],1),E(i,N+R[i],1),E(N+L[i],M-1,1-B[L[i]]),B[L[i]]=1,E(N+R[i],M-1,1-B[R[i]]),B[R[i]]=1;wt(f.solve(M-2,M-1));