Problem1378--C二级辅导-正对角线和

1378: C二级辅导-正对角线和

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 203  Solved: 145
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Description

求一个3×3矩阵正对角线元素之和。

Sample Input Copy

1 2 3
4 5 6
7 8 9

Sample Output Copy

15

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