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  1. #include<stdio.h>
  2. int main()
  3. {
  4. 	long t;
  5. 	int b,m,i,a[40],j,x,y;
  6. 	scanf("%ld",&t);
  7. 	while(t--)
  8. 	{
  9. 	    scanf("%d%d",&b,&m);
  10. 	    i=0,j=0;
  11. 	    while(i<m)
  12. 		{
  13. 			scanf("%d%d",&a[j],&a[j+1]);
  14. 			j+=2,++i;
  15. 		}
  16. 		if(b<=2)
  17. 		printf("YES\n");
  18. 		else if(b==3)
  19. 		{
  20. 			x=a[0],y=a[1];
  21. 			for(i=1,j=2;i<m;i++,j+=2)
  22. 			{
  23. 				if(x==a[j]||x==a[j+1]);
  24. 			    else
  25. 			    break;
  26. 			}
  27. 			if(i==m)
  28. 			printf("YES\n");
  29. 			else
  30. 			{
  31. 			for(i=1,j=2;i<m;i++,j+=2)
  32. 			{
  33. 				if(y==a[j]||y==a[j+1]);
  34. 			    else
  35. 			    break;
  36. 			}
  37. 			if(i==m)
  38. 			printf("YES\n");
  39. 			else
  40. 			printf("NO\n");
  41. 		    }
  42. 		}
  43. 		else
  44. 		printf("NO\n");
  45.    }
  46. 	    return 0;	
  47. }
Success #stdin #stdout 0s 2252KB
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YES
https://ideone.com/brFJv7
language:
C (gcc 8.3)
created:
9 years ago
visibility:
public

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