#include<iostream> 
  using namespace std; 
    
  // Maximum number of digits in output 
  #define MAX 500 
    
  int multiply(int x, int res[], int res_size); 
  void factorial(int n); 
    
  // This function finds factorial of large numbers and prints them 
  void factorial(int n) 
  { 
      int res[MAX]; 
    
      // Initialize result 
      res[0] = 1; 
      int res_size = 1; 
    
      // Apply simple factorial formula n! = 1 * 2 * 3 * 4...*n 
      for (int x=2; x<=n; x++) 
          res_size = multiply(x, res, res_size); 
    
      cout << "Factorial of given number is \n"; 
      for (int i=res_size-1; i>=0; i--) 
          cout << res[i]; 
  } 
    
  // This function multiplies x with the number represented by res[]. 
  // res_size is size of res[] or number of digits in the number represented 
  // by res[]. This function uses simple school mathematics for multiplication. 
  // This function may value of res_size and returns the new value of res_size 
  int multiply(int x, int res[], int res_size) 
  { 
      int carry = 0;  // Initialize carry 
    
      // One by one multiply n with individual digits of res[] 
      for (int i=0; i<res_size; i++) 
      { 
          int prod = res[i] * x + carry; 
          res[i] = prod % 10;  // Store last digit of 'prod' in res[] 
          carry  = prod/10;    // Put rest in carry 
      } 
    
      // Put carry in res and increase result size 
      while (carry) 
      { 
          res[res_size] = carry%10; 
          carry = carry/10; 
          res_size++; 
      } 
      return res_size; 
  } 
    
  // Driver program 
  int main() 
  { 
      factorial(100); 
      return 0; 
  }