整张表里有几个 1

五个人、四段关系，建成邻接矩阵。运行下面这段程序：

NAMES = ["阿岚", "小满", "阿泰", "南风", "北辰"]
EDGES = [("阿岚", "小满"), ("阿岚", "阿泰"),
         ("小满", "阿泰"), ("阿泰", "南风")]

def build_mat():
    n = len(NAMES)
    m = [[0] * n for _ in range(n)]
    for a, b in EDGES:
        i = NAMES.index(a)
        j = NAMES.index(b)
        m[i][j] = 1
        m[j][i] = 1
    return m

m = build_mat()
n = 0
for row in m:
    n += sum(row)
print(n)