/in/foo.cc: In function 'int main()':
/in/foo.cc:81:9: warning: 'flag' may be used uninitialized in this function [-Wmaybe-uninitialized]
         if(flag) cout<<a-b<<endl;
         ^~
/in/foo.cc:14:14: warning: 'loc2' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int loc1,loc2,flag;//flag 0+  1-
              ^~~~
/in/foo.cc:14:9: warning: 'loc1' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int loc1,loc2,flag;//flag 0+  1-
         ^~~~