import sys
sys.setrecursionlimit(10**6)

n,m = map(int,input().split())
ue=[[] for i in range(n)]
shita=[[] for i in range(n)]
for i in range(m):
    x,y=map(int,input().split())
    x-=1
    y-=1
    ue[x].append(y)
    shita[y].append(x)
    ue[y].append(x)
    shita[x].append(y)


fu = [0]*n
fs = [0]*n
def  cal(x,f):
    if f == 0:
        fu[x] = 1
        for i in ue[x]:
            if fs[i] == 0:
                cal(i,1)
    else:
        fs[x] = 1
        for i in shita[x]:
            if fu[i] == 0:
                cal(i,0)

for i in range(n):
    if fu[i] == 0 and fs[i] == 0:
        cal(i,0)

if all(fu) and all(fs):
    print('Yes')
else:
    print('No')