#include <stdio.h>
int f( int x );
int main ()
{
int body,head,left,right,m,n;
scanf("%d %d",&m,&n);
int a;
head = f(n);//求出分子部分
left = f(m);//求出分母部分的左边(m!)
a = n - m;
right = f(a);//求出分母部分的右边(n - m )!
body = left * right;//分母部分
printf("result = %d",head / body );
}
int f(int x)//对x进行阶乘
{
int i;
int sum=1;
for(i=1;i<=x;i++)
{
sum *= i;
}
return sum;
}