#!/bin/python3

import sys

def countArray(n, k, x):
    # Return the number of ways to fill in the array.
    if((n-2)<k):
       l = n-2
       pos = (l-1)*(k-1)+k-2
    else:
       l = n-2
       pos = l*(k-1)/(round(l/2))
    return pos
if __name__ == "__main__":
    n, k, x = input().strip().split(' ')
    n, k, x = [int(n), int(k), int(x)]
    answer = countArray(n, k, x)
    print(answer)