#P699. c++L12主对角线的元素之和
c++L12主对角线的元素之和

Samples
3
1 2 3
4 5 6
7 8 9
15
Limitation
1s, 1024KiB for each test case.

3
1 2 3
4 5 6
7 8 9
15
1s, 1024KiB for each test case.