View Compilation Error

0_0_37512406_31081.cpp: In function 'Poly operator*(const Poly&, const Poly&)':
0_0_37512406_31081.cpp:80:10: error: redeclaration of 'Poly c'
   Poly c(min(int(a.size() + b.size()), m + 1));
          ^
0_0_37512406_31081.cpp:73:15: note: 'Poly c' previously declared here
   static Poly c;
               ^