#include <iostream>

using namespace std;

// global - yuk!
int indenting = 0;

int factorial(int x) {
   indenting++;
   for(int i = 0; i < indenting - 1; i++ ) { cout << "    "; }
   
   // base case
   if(x==0) {
      cout << "1" << endl;
      indenting--;
      return 1;
   // recurrence case
   } else {
      cout << x << " * factorial(" << x - 1 << ")"  << endl;
      int result = factorial(x-1);
      indenting--;
      return x * result;
   }
}


int main(int argc, char** argv) {

   if(argc!=2) {
      cerr << "Usage: " << argv[0] << " n" << endl;
      exit(EXIT_FAILURE);
   }

   int x = atoi(argv[1]);
   cout << endl << "factorial(" << x << "): " << factorial(x) << endl;
   
   return EXIT_FAILURE;
}