class Route(object):
    """docstring for Route."""
    def __init__(self, route_id, contract_id, load,src,dst):
        super(Route, self).__init__()
        self.route_id = route_id
        self.contract_id = contract_id
        self.load = load
        self.src = src
        self.dst = dst

    def __eq__(self,rt):
        eq = self.route_id == rt.route_id and self.contract_id == rt.contract_id
        return eq

    def __repr__(self):
        return str(self.contract_id)+"-"+str(self.route_id)+":"+self.src+" - "+self.dst+" "+self.load


class Contract(object):
    """docstring for Contract."""
    def __init__(self, contract_id, routes):
        super(Contract, self).__init__()
        self.contract_id = contract_id
        self.routes = routes

    def __repr__(self):
        return "\tContract : "+str(self.contract_id)+"\n\tRoutes\n\t\t"+"\n\t\t".join(map(repr,self.routes))

class Transporter(object):
    """docstring for Transporter."""
    def __init__(self, contracts):
        super(Transporter, self).__init__()
        self.contracts = contracts

    @classmethod
    def from_file(cls,c_file):
        return cls(cls.read_contracts(c_file))

    @staticmethod
    def read_contracts(c_file):
        c_lines = open(c_file,'r').readlines()
        c_dict = {}
        for l in c_lines:
            (c_id,src,dst,load) = l.split(' ')
            if c_dict.has_key(c_id):
                route_id = len(c_dict[c_id])
                c_dict[c_id].append(Route(route_id,int(c_id),load,src,dst))
            else:
                c_dict[c_id] = [Route(0,int(c_id),load,src,dst)]
        contracts = [Contract(int(i),c_dict[i]) for i in sorted(c_dict.keys())]

        return contracts

    def contract_routes(self):
        all_routes = []
        for c in self.contracts:
            for r in c.routes:
                all_routes.append(r)
        return all_routes

    def contracts_required(self):
        routes = self.contract_routes()
        unfulfilled = rem_routes(routes)
        print "No of contracts required : ",len(unfulfilled)
        if len(unfulfilled) > 0:
            print "Contracts from ",repr(unfulfilled)

CYCLE_LIMIT = 3

def rem_routes(routes):
    loop_routes = routes
    while len(loop_routes)>0:
        circ,paths,loop_routes = largest_loop(loop_routes)
        if not circ:
            break
    partial_paths = []
    partial_routes = loop_routes
    while len(partial_routes)>0:
        lp = longest_path(partial_routes)
        partial_paths.append((lp[-1].dst,lp[0].src))
        partial_routes = filter(lambda x:x not in lp,partial_routes)
    return partial_paths

def route_deps(routes):
    routes_map = {}
    for r in routes:
        if routes_map.has_key(r.src):
            routes_map[r.src].append(r)
        else:
            routes_map[r.src]= [r]
        if not routes_map.has_key(r.dst):
            routes_map[r.dst]= []
    return routes_map

def largest_loop(routes):
    deps = route_deps(routes)
    circ_paths = [find_loop(r.src,r.src,deps,set(),[]) for r in routes]
    circ,paths = max(circ_paths,key=lambda p:len(p[1]))
    # print filter(lambda p:not p[0],circ_paths)
    rem_paths = filter(lambda x:x not in paths,routes)
    return (circ,paths,rem_paths)

def longest_path(routes):
    def route_path(r,deps):
        if not deps.has_key(r.dst) or len(deps[r.dst])==0:
            return [r]
        all_dep_paths = [([r]+route_path(rt,deps)) for rt in deps[r.dst]]
        rp = max(all_dep_paths,key=lambda p:len(p))
        return rp
    deps = route_deps(routes)
    all_paths = [route_path(r,deps) for r in routes]
    longest = max(all_paths,key=len)
    return longest

def find_loop(elem,dep_elem,deps,checked,path):
    found_loop = False
    if dep_elem not in checked and deps.has_key(dep_elem):
        checked.add(dep_elem)
        for c in deps[dep_elem]:
            path.append(c)
            if elem == c.dst and len(path) <= CYCLE_LIMIT:
                found_loop = True
                break
            (loop,path) = find_loop(elem,c.dst,deps,checked,path)
            if loop:
                found_loop = True
                break
            else:
                del(path[-1])
    return (found_loop,path)


# Transporter.from_file('./contracts.txt').contracts_required()
Transporter.from_file('./contracts.txt').contracts_required()