#include<cstdio>
#include<cstdlib>

int n,m;
int p1,p2;
int pomi;

void read();
int cmmdc(int x, int y);
void write();

int main() {
	read();
	write();
}

void read() {
	freopen("mins.in","r",stdin);
	scanf("%d%d%d%d",&n,&m,&p1,&p2);
}

int cmmdc(int x, int y) {
	if (y==0) return x;
	return cmmdc(y,x%y);
}

void write() {
	freopen("mins.out","w",stdout);
	int i,j,c;
	for (i=1;i<n;++i)
		if (m-1>i)
			pomi+=m-1;
		else if (m-1==i)
			pomi+=m-2;
		else {
			pomi+=(m-1)/i;
			pomi+=(m-1)%i;
		}
	printf("%d",pomi);
}