哎。。。比赛的时候漏掉了一个地方没考虑。。

#include <iostream>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <climits>  
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 1005
#define maxm 40005
#define eps 1e-10
#define mod 1000000007
#define INF 999999999
#define lowbit(x) (x&(-x))
#define mp mark_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid  
#define rson o<<1 | 1, mid+1, R  
typedef long long LL;
//typedef int LL;
using namespace std;
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
void scanf(LL &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}
LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}
// head

int main(void)
{
	int n, k, x, y, sum;
	while(scanf("%d%d", &n, &k)!=EOF) {
		x = sqrt(n);
		if(x * x == n) x--;
		y = n - x * x;
		sum = (k-1)*k/2;
		if(y > k) sum += y;
		else {
			sum += k;
			if(y == k && sum == n-1) {
				printf("NO\n");
				continue;
			}
		}
		if(sum <= n) printf("YES\n");
		else printf("NO\n");
	}
	return 0;
}