n = int(input())
matrix = []
for _ in range(n):
    row = list(map(int,input().split()))
    matrix.append(row)

is_upper = True
for i in range(n):
    for j in range(n):
        if i > j and matrix[i][j] != 0:
            is_upper = False
            break
        if not is_upper:
            break
print("YES"if is_upper else "NO")