View Compilation Error

0_0_17840725_6446.cpp: In function 'int main()':
0_0_17840725_6446.cpp:71:70: error: expected ']' before ')' token
                         ans=(ans+add*pow2[(sheng-now)*(sheng-now-1)/2)]%mod;
                                                                      ^
0_0_17840725_6446.cpp:71:71: error: expected ';' before ']' token
                         ans=(ans+add*pow2[(sheng-now)*(sheng-now-1)/2)]%mod;
                                                                       ^