Baobab

n = int(input())
g = []
for i in range(n):
    g.append(list(map(int, input().split())))

visited = [0] * 100
def dfs(node, parent):
    if visited[node]:
        return False
    visited[node] = 1
    for neigh, conn in enumerate(g[node]):
        if conn and neigh != parent:
            if not dfs(neigh, node):
                return False
    return True

count = 0
res = 'YES'
for node in range(n):
    if not visited[node]:
        count += 1
        if count > 1 or not dfs(node, -1):
            res = 'NO'
            break

print(res)