X-mart AC

#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <vector>
#include <stack>
using namespace std;

#define MAXP 10010

int c,p;
vector<int> adj[2*MAXP];
int num[2*MAXP];
int low[2*MAXP];
int scc[2*MAXP];
stack<int> s;
int inSt[2*MAXP];
int nDfs, nScc;

inline int neg(int x) {
    return x+p;
}

void addEdge(int a, int b, bool del) {
    if (!a && !b) return;
    if (a>b) swap(a,b);

    if (!a) {
        if (del) adj[b-1].push_back(neg(b-1));
        else adj[neg(b-1)].push_back(b-1);
        return;
    }

    if (del) {
        adj[b-1].push_back(neg(a-1));
        adj[a-1].push_back(neg(b-1));
    }
    else {
        adj[neg(b-1)].push_back(a-1);
        adj[neg(a-1)].push_back(b-1);
    }
}

void tarjanScc(int v) {
    num[v]=low[v]=nDfs++;
    s.push(v), inSt[v]=true;

    for (int i=0; i<(int)adj[v].size(); i++) {
        int w=adj[v][i];

        if (num[w]==-1) {
            tarjanScc(w);
            low[v]=min(low[v],low[w]);
        }
        else
            if (inSt[w])
                low[v]=min(low[v],num[w]);
    }

    if (low[v]==num[v]) {
        int t;
        do {
            t=s.top();
            inSt[t]=false;
            scc[t]=nScc;
            s.pop();
        } while (t!=v);

        nScc++;
    }
}

int main() {
    while (1) {
        scanf("%d %d", &c,&p);
        if (!c && !p) break;

        for (int i=0; i<2*p; i++)
            adj[i].clear();

        for (int i=0; i<c; i++) {
            int X,Y,S,T;
            scanf("%d %d %d %d", &X,&Y,&S,&T);

            addEdge(X,Y,false);
            addEdge(S,T,true);
        }

        memset(num,-1,sizeof(num));
        memset(low,-1,sizeof(low));
        memset(inSt,false,sizeof(inSt));
        while (!s.empty()) s.pop();
        nDfs=0, nScc=0;

        for (int i=0; i<2*p; i++)
            if (num[i]==-1) tarjanScc(i);
        bool sat=true;

        for (int i=0; i<p; i++)
            sat=sat&&(scc[i]!=scc[neg(i)]);

        printf("%s\n", sat? "yes":"no");
    }
    return 0;
}