/in/foo.c: In function 'main':
/in/foo.c:3:12: warning: variable 'n' set but not used [-Wunused-but-set-variable]
  int a,b,c,n;
            ^
/in/foo.c:4:5: warning: 'a' is used uninitialized in this function [-Wuninitialized]
  n=a+b+c;
     ^
/in/foo.c:4:5: warning: 'b' is used uninitialized in this function [-Wuninitialized]
/in/foo.c:4:7: warning: 'c' is used uninitialized in this function [-Wuninitialized]
  n=a+b+c;
       ^