> #include<iostream>
> using namespace std;
> #include<fstream>
> 
> void shaixuan(int & m,int& n,int c,char op,int & x)
> {
> 	if(op=='AND'&&c==1)
> 	{
> 		if(m==-1&&n==-1)
> 		{
> 			m=n=1; x=-1;
> 		}
> 		else if(m==0||n==0)
> 		{
> 			cout<<"NO"<<endl; exit(0);
> 		}
> 	}//-----------------------------------------------------------
> 	if(op=='OR'&&c==0)
> 	{
> 		if(m==-1&&n==-1)
> 		{
> 	     	m=n=0; x=-1;
> 		}
>         else if(m==1||n==1)
> 		{
>             cout<<"NO"<<endl; exit(0);
> 		}
> 	}//----------------------------------------------------------
> 	if(op=='XOR'&&c==0)
> 	{
>         if(m==1&&n==0||m==0&&n==1)
> 		{
> 			cout<<"NO"<<endl; exit(0);
> 		}
> 		if(m==1&&n==-1)
> 		{
> 			n=1; x=-1;
> 		}
> 	    
> 		else if(m==0&&n==-1)
> 		{	
> 			n=0; x=-1;
> 		}
> 		
> 		else if(m==-1&&n==1)
> 		{
> 			m=1; x=-1;
> 		}
> 		
> 		else if(m==-1&&n==0)
> 		{	
> 			m=0; x=-1;
> 		}
> 		
> 		
> 	}
> 	if(op=='XOR'&&c==1)
> 	{
> 		if(m==1&&n==1||m==0&&n==0)
> 		{
> 			cout<<"NO"<<endl;
> 		}
> 		else if(m==1&&n==-1)
> 		{	n=0; x=-1;}
> 		else if(m==0&&n==-1)
> 		{  n=1;x=-1;}
>         
> 		else if(m==-1&&n==1)
> 		{	m=0; x=-1;}
> 		else if(m==-1&&n==0)
> 		{  m=1;x=-1;}
> 
> 	}
> }
> 
> struct info
> {
> 	int m;
> 	int n;
> 	int c;
> 	char op;
> 	int flag;
> } ;
> 
> 
> int main()
> {
> 	ifstream fin("11.in");
> 	struct info edge[10000];
> 	int i;
> 	int x[1000];
> 	int n,m;  
> 	fin>>n>>m;
> 	for(i=0;i<m;i++)
> 	{
> 		fin>>edge[i].m>>edge[i].n>>edge[i].c>>edge[i].op;
> 		edge[i].flag =0;
>         shaixuan ( x[edge[i].m] , x[edge[i].n] , edge[i].c ,edge[i].op ,edge[i].flag );
> 	}
> 
>     cout<<"YES"<<endl;
> 	return 0;
> }