题解 | 调皮的依依

# import sys

# for line in sys.stdin:
#     a = line.split()
#     print(int(a[0]) + int(a[1]))
n=int(input())
m=int(input())
lst=list(map(int,input().split()))
ary=[i for i in range(1,n+1)]
res=set(ary)-set(lst)
if len(res)==1 and sorted(lst)==lst:
    print("Yes")
    temp=list(res)
    print(temp[0])
else:
    print("No")