#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>

using namespace std;

typedef long long ll;

int main()
{
	ll n,a,b;
	cin >> n >> a >> b;
	if(a>b)
		printf("%d\n", 0);
	else if(a==b)
		printf("%lld\n", 1);
	else{
		if(n==1)
			printf("%d\n", 0);
		else{
			ll sum=2;
			ll num=b-a+1;
			ll sum1=1;
			for(ll i=num;i>=n-1;i--)
				sum1*=i;
			sum+=sum1;
			printf("%lld\n", sum);

		}
	}
	return 0;
}
