import sys
input = sys.stdin.readline

N,M,K,s,t=map(int,input().split())

E=[[] for i in range(N+1)]

for i in range(M):
    x,y=map(int,input().split())
    E[x].append(y)
    E[y].append(x)

if K==1:
    print("Yes")
    exit()

if E[s]==[] and E[t]==[]:
    print("No")
    exit()

print("Yes")