// fac25.cpp - CALCULATE 25 FACTORIAL
//
// MAINTENANCE HISTORY
// DATE         PROGRAMMER AND DETAILS
// 22-10-03     JS      Original
//
//-----------------------------------------------------------------------------

#include <stdio.h>              // Standard input/output
#include <string.h>             // String manipulation functions

//-----------------------------------------------------------------------------

// DEFINITIONS

#define PRECISION       30      // Precision of number in decimal digits

//-----------------------------------------------------------------------------

// MAIN LINE

int
main ()
{
    char                reg[PRECISION]; // Extended precision register
    int                 i, j;           // General purpose indices
    int                 carry;          // Carry value

    // Initialise the register (reg = 1)

    memset (reg, 0, PRECISION);
    reg[0] = 1;

    // Multiply reg by 2, 3 ... 25

    for (i = 2; i <= 25; i++) {
        carry = 0;
        for (j = 0; j < PRECISION; j++) {
            carry += reg[j] * i;
            reg[j] = carry % 10;
            carry /= 10;
        }
    }

    // Display the result

    for (j = PRECISION-1; j > 0 && reg[j] == 0; j--);
    for (; j >= 0; j--) putchar(reg[j] + '0');
    putchar('\n');

    // Exit gracefully

    return 0;
}