#1
'''n = int(input())
c = 0
for i in range(n):
A = list(map(int, input().split()))
for i in A:
if i == 1:
c += 1
print(c)'''
#2
'''n, m = map(int, input().split())
Gi = [set() for i in range(n+1)]
Gv = [set() for i in range(n+1)]
for i in range(m):
v1, v2 = map(int, input().split())
Gi[v1].add(v2)
Gv[v2].add(v1)
for i in range(1, n+1):
print(len(Gv[i]))
print(len(Gi[i]))'''
#3
'''n = int(input())
A = []
for i in range(n):
A.append(list(map(int, input().split())))
c = 0
for i in range(n):
for j in range(n):
if A[i][j] == 1:
c += 1
A[j][i] = 0
print(c)'''
#4
'''n, m = map(int, input().split())
G = [set() for i in range(n+1)]
for i in range(m):
v1, v2 = map(int, input().split())
G[v1].add(v2)
G[v2].add(v1)
c = len(G[1])
f = 0
for i in range(2, n+1):
if len(G[i]) != c:
print('NO')
f = 1
break
if f != 1:
print('YES')'''