foo.cpp: In member function 'void Bignum::Check()':
foo.cpp:22:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 1; i < v.size(); i++) {
                             ^
foo.cpp: In member function 'Bignum& Bignum::operator*=(int)':
foo.cpp:33:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < v.size(); i++) {
                             ^
foo.cpp: In function 'int main()':
foo.cpp:75:22: error: 'struct Node' has no member named 'a'
     cin>>n>>v.back().a>>v.back().b;
                      ^
foo.cpp:75:34: error: 'struct Node' has no member named 'b'
     cin>>n>>v.back().a>>v.back().b;
                                  ^
foo.cpp:79:23: error: 'struct Node' has no member named 'a'
         cin>>v.back().a>>v.back().b;
                       ^
foo.cpp:79:35: error: 'struct Node' has no member named 'b'
         cin>>v.back().a>>v.back().b;
                                   ^
foo.cpp:82:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1; i!=v.size(); ++i)
                            ^
foo.cpp:84:19: error: 'struct Node' has no member named 'a'
         s*=v[i-1].a;
                   ^
foo.cpp:85:28: error: 'struct Node' has no member named 'b'
         ans=max(ans,s/v[i].b);
                            ^