/in/foo.cc: In function 'int main()':
/in/foo.cc:25:15: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'int*' [-Wformat=]
  printf("%s",k);
               ^
/in/foo.cc:10:7: warning: variable 'c' set but not used [-Wunused-but-set-variable]
  char c[a+1],z[b+1];
       ^
/in/foo.cc:10:14: warning: unused variable 'z' [-Wunused-variable]
  char c[a+1],z[b+1];
              ^