My solution of code forces round div 3 for C (train queries) was hacked and I didn't find the case where I would fail.Please help me find that case. I really appreciate any help you can provide.
Here is my code ```
def solve(): d = defaultdict(list)
# n = int(input()) # s=input() e=input() n,m=list(map(int,input().split())) # lis = list(map(int, input().split())) # lis1=input().split() # lis2 = list(map(int, input().split())) # lis3 = list(map(int, input().split())) # n,r,b=list(map(int,input().split())) # order=list(map(int,input().split())) # r2,c2=list(map(int,input().split())) # ans=[[-1 for _ in range(m)] for _ in rnage(n)] for i,ele in enumerate(lis): d[ele].append(i) for _ in range(m): u,v=list(map(int,input().split())) if(u not in d or v not in d): print("NO") continue if(d[u][0]<d[v][-1]): print("YES") else: print("NO")
```