/in/foo.cc: In function 'void exgcd(long long unsigned int, long long unsigned int, long long unsigned int&, long long unsigned int&)':
/in/foo.cc:14:20: warning: value computed is not used [-Wunused-value]
  (y-=a/b*x%mod-mod)%mod;
                    ^
/in/foo.cc: In function 'long long unsigned int C(long long unsigned int, long long unsigned int)':
/in/foo.cc:32:6: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(m==-1) return 1;
     ~^~~~
/in/foo.cc: In function 'long long unsigned int fC(long long unsigned int, long long unsigned int)':
/in/foo.cc:37:6: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if(m==-1) return 1;
     ~^~~~