foo.cc: In function ‘int main()’:
foo.cc:35:18: warning: ‘a’ may be used uninitialized [-Wmaybe-uninitialized]
   35 |         cout<<a<<" "<<b<<endl;
      |                  ^~~
foo.cc:10:27: note: ‘a’ was declared here
   10 |         int fenzi,fenmu,r,a,b,f1,f2;
      |                           ^
foo.cc:35:23: warning: ‘b’ may be used uninitialized [-Wmaybe-uninitialized]
   35 |         cout<<a<<" "<<b<<endl;
      |                       ^
foo.cc:10:29: note: ‘b’ was declared here
   10 |         int fenzi,fenmu,r,a,b,f1,f2;
      |                             ^