#include <bits/stdc++.h>
using namespace std;
#define ll long long
namespace IO {
	#if ONLINE_JUDGE
	#define getc() (IS == IT && (IT = (IS = ibuf) + fread(ibuf, 1, IL, stdin), IS == IT) ? EOF : *IS++)
	#else
	#define getc() getchar()
	#endif
	const int IL = 1 << 21, OL = 1 << 21;
	int olen = 0;
	char ibuf[IL], *IS = ibuf, *IT = ibuf, obuf[OL];
	inline int read() {
		register char ch = getc(); register int x = 0, f = 1;
		while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getc(); }
		while(isdigit(ch)) x = x * 10 + ch - 48, ch = getc();
		return x * f;
	}
	inline double readdb() {
		register char ch = getc(); register double x = 0, f = 1;
		while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getc(); }
		while(isdigit(ch)) x = x * 10 + ch - 48, ch = getc();
		if(ch == '.') {
			register double b = 0.1;
			ch = getc();
			while(isdigit(ch)) x += (ch - 48) * b, b *= 0.1, ch = getc();
		}
		return x * f;
	}
	inline int readstr(char *s) {
		register char ch = getc(); register int len = 0;
		while(!isalpha(ch)) ch = getc();
		while(isalpha(ch)) s[++len] = ch, ch = getc();
		return len;
	}
	inline void flush() { fwrite(obuf, 1, olen, stdout); olen = 0; }
	inline void putc(register char ch) { obuf[olen++] = ch; }
	template<class T>
	inline void write(register T x) {
		if(x < 0) obuf[olen++] = '-', x = -x;
		if(x > 9) write(x / 10);
		obuf[olen++] = x % 10 + 48;
	}
} using namespace IO;
const int N = 1e6 + 10;
int n, l, r;
struct edge {
	int u, v;
	ll w;
} e[N * 10];
int cnt; 
int fa[N];
int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }
bool cmp(edge x, edge y) {
	return x.w < y.w;
}
ll lcm(int x, int y) {
	return 1ll * x * y / __gcd(x, y);
}
int main() {
	l = read(), r = read();
	if(l == r) {
		puts("0");
		return 0;
	}
	n = r - l + 1;
	for(int i = l; i <= r; i++) {
		for(int j = 1; j * j <= i; j++)
			if(i % j == 0) {
				int x = l / j;
				while(x * j < l || x * j == i) x++;
//				cout << x * j << " " << i << endl;
				if(x * j <= r) e[++cnt] = {x * j, i, lcm(x * j, i)};
				int t = i / j;
				if(t == j) continue; 
				x = l / t;
				while(x * t < l || x * t == i) x++;
				if(x * t <= r) e[++cnt] = {x * t, i, lcm(x * t, i)};
			}
	}
	sort(e + 1, e + 1 + cnt, cmp);
	for(int i = l; i <= r; i++)
		fa[i] = i;
	ll ans = 0; 
	for(int i = 1; i <= cnt; i++) {
		int x = find(e[i].u), y = find(e[i].v);
		if(x == y) continue;
		fa[x] = y;
		ans += e[i].w; 
	}
	printf("%lld\n", ans);
	return 0;
}