/in/foo.cc: In function 'int main()':
/in/foo.cc:19:31: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[10001]' [-Wformat=]
  scanf("%s%s%s", &s1, &s2, &s3);
                               ^
/in/foo.cc:19:31: warning: format '%s' expects argument of type 'char*', but argument 3 has type 'char (*)[10001]' [-Wformat=]
/in/foo.cc:19:31: warning: format '%s' expects argument of type 'char*', but argument 4 has type 'char (*)[10001]' [-Wformat=]
/in/foo.cc:15:9: warning: unused variable 'k' [-Wunused-variable]
  int n, k;
         ^