View Compilation Error

0_0_25339740_27736.cpp:15:17: error: 'M_PI' was not declared in this scope
 const double pi=M_PI;
                 ^
0_0_25339740_27736.cpp: In function 'int main()':
0_0_25339740_27736.cpp:45:51: error: lvalue required as left operand of assignment
   for(int i=0,l=strlen(s1);i<l;i++)a[l-i-1].real()=(s1[i]-'0');
                                                   ^
0_0_25339740_27736.cpp:46:51: error: lvalue required as left operand of assignment
   for(int i=0,l=strlen(s2);i<l;i++)b[l-i-1].real()=(s2[i]-'0');
                                                   ^