#include <stdio.h>

int min(int x,int y){
	if(x <= y)
		return x;
	else
		return y;
	}

long bc(int n,int k,int m){
	int i;
	long ans = 0;

	if(n == 0 && k == 0)
		return 1;

	for(i = 1;i <= min(n,m);i++)
		ans += bc(n - i,k - 1,m);
	return ans;
	}

int main(){
int n,m,k;
scanf("%d %d %d",&n,&k,&m);
printf("\nans = %ld\n",bc(n,k,m));
return 0;
}