250729
#include <stdio.h>
int i=1, incr=1, pascar=1;
int pascal(int f, int g)
{
if(i<f)
{
pascar+=incr;
incr=incr+g-2;
i++;
pascal(f, g);
}
return pascar;
}
int main()
{
int i, j, r, t, o=1;
scanf("%d %d", &r, &t);
incr=t-1;
printf("%d", pascal(r, t));
}