/in/foo.cc: In function 'int main()':
/in/foo.cc:25:7: warning: variable 'a' set but not used [-Wunused-but-set-variable]
   int a,k,n,c,i;
       ^
/in/foo.cc:25:13: warning: variable 'c' set but not used [-Wunused-but-set-variable]
   int a,k,n,c,i;
             ^
/in/foo.cc:25:15: warning: unused variable 'i' [-Wunused-variable]
   int a,k,n,c,i;
               ^