/in/foo.cc: In function 'int main()':
/in/foo.cc:6:15: warning: unused variable 'w' [-Wunused-variable]
    6 |         float w;
      |               ^
/in/foo.cc:7:12: warning: 'm' is used uninitialized [-Wuninitialized]
    7 |         b=m*20;
      |           ~^~~
/in/foo.cc:5:17: note: 'm' declared here
    5 |         float a,m,k,b,c;
      |                 ^
/in/foo.cc:8:12: warning: 'a' is used uninitialized [-Wuninitialized]
    8 |         c=a-b;
      |           ~^~
/in/foo.cc:5:15: note: 'a' declared here
    5 |         float a,m,k,b,c;
      |               ^