/in/foo.cc: In function 'void solve()':
/in/foo.cc:40:63: error: expected ')' before ';' token
  ans=(((a%MOD*(d%MOD)%MOD-(b%MOD*(c%MOD)%MOD+MOD)%MOD+MOD)%MOD;
                                                               ^
/in/foo.cc:40:63: error: expected ')' before ';' token
/in/foo.cc:41:13: error: 'mod' was not declared in this scope
  cout<<(((a%mod)*(d%mod) - (b%mod)*(c%mod))%mod+mod)%mod;
             ^~~