/in/foo.cc: In function 'int main()':
/in/foo.cc:19:16: warning: format '%c' expects argument of type 'char*', but argument 2 has type 'int*' [-Wformat=]
  scanf("%c",&nn);
                ^
/in/foo.cc:23:17: warning: format '%c' expects argument of type 'char*', but argument 2 has type 'int*' [-Wformat=]
   scanf("%c",&nn);
                 ^