/in/foo.c: In function 'ks':
/in/foo.c:8:6: warning: unused variable 'c1' [-Wunused-variable]
  int c1=c; 
      ^~
/in/foo.c: In function 'main':
/in/foo.c:43:10: warning: unused variable 'k' [-Wunused-variable]
  int i,j,k,n,sum;
          ^
/in/foo.c:43:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,k,n,sum;
        ^
/in/foo.c:43:6: warning: unused variable 'i' [-Wunused-variable]
  int i,j,k,n,sum;
      ^