from collections import defaultdict


class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        way=[]
        while True:
            if self.parents[x] < 0:
                break
            else:
                way.append(x)
                x=self.parents[x]
        for w in way:
            self.parents[w]=x
        return x

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return

        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        group_members = defaultdict(list)
        for member in range(self.n):
            group_members[self.find(member)].append(member)
        return group_members

    def __str__(self):
        return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items())
    

N,M=map(int,input().split())
S=set()
for _ in range(M):
    S.add(input())
#if '1'*N not in S:
#    print('No')
#    exit(0)
Flag=[[True for _ in range(N)] for _ in range(N)]
for s in S:
    for i in range(N):
        for j in range(N):
            if s[i]!=s[j]:
                Flag[i][j]=False
uf=UnionFind(N)
for i in range(N):
    for j in range(N):
        if Flag[i][j]:
            uf.union(i,j)
#print(Flag)
if 2**uf.group_count()>len(S):
    print('No')
else:
    print('Yes')