if(e[i^1].flow&&dist[v]>dist[u]-e[i].cost){
            	dist[v]=dist[u]-e[i].cost;
            	if(!ck[v]){
            	    ck[v]=1;
           	    	if(!q.empty()&&dist[q.front()]>dist[v]) q.push_front(v);
					else q.push_back(v);
            	}
        	}