foo.cc: In function 'Iv MUl(const Iv&, int)':
foo.cc:38:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<A.size() || t;i++)
                 ~^~~~~~~~~
foo.cc:40:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(i<A.size())
            ~^~~~~~~~~
foo.cc: In function 'Iv Add(const Iv&, const Iv&)':
foo.cc:51:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<A.size() || i<B.size();i++)
                 ~^~~~~~~~~
foo.cc:51:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<A.size() || i<B.size();i++)
                               ~^~~~~~~~~
foo.cc:54:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(i<A.size()) t+=A[i];
            ~^~~~~~~~~
foo.cc:55:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(i<B.size()) t+=B[i];
            ~^~~~~~~~~
foo.cc: In function 'Iv Mul_vtv(const Iv&, const Iv&)':
foo.cc:65:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(register int i=0;i<B.size();i++)
                          ~^~~~~~~~~

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