D. DP Killer - 2018.9 ECNU ICPC/CCPC Trial Round #1 - ECNU Online Judge

你可以在这里下载。

单点时限: 2.0 sec

内存限制: 512 MB

样例

Input

3 3
1+2
+9*
1*5

Output

Input

1 31
9*9*9*9*9*9*9*9*9*9*9*9*9*9*9*9

Output

-1

Input

5 5
2+2+1
+1+1+
1+2+2
+1+1+
1+1+2

Output

Input

9 7
8+9*4*8
*5*2+3+
1*3*2*2
*5*1+9+
1+2*2*2
*3*6*2*
7*7+6*5
*5+7*2+
3+3*6+8

Output

NaN

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