題目連結

#include<bits/stdc++.h>
using namespace std;
#define cl(a,b) memset(a,b,sizeof(a))
#define fastIO ios::sync_with_stdio(false);cin.tie(0);
#define LL long long
#define pb push_back
#define gcd __gcd

#define For(i,j,k) for(int i=(j);i<k;i++)
#define lowbit(i) (i&(-i))
#define _(x) printf("%d\n",x)
 


const double EPS = 1e-8;
const int maxn = 5e6+10;
const int inf  = 1 << 28;

/*
[0,n]之間的尤拉函式值
*/
int phi[maxn];
void getPhi(int n){
    cl(phi,0);phi[1]=1;
    for(int i=2;i<=n;i++)if(!phi[i]){
        for(int j=i;j<=n;j+=i){
            if(!phi[j])phi[j]=j;
            phi[j]=phi[j]/i*(i-1);
        }
    }
}

int
 
 main(){
    int L,R;
    cin>>L>>R;
    getPhi(R);
    int ans = R,val = R;
    for(int i=L;i<=R;i++){
        if(phi[i]<val){
            val = phi[i];
            ans = i;
        }
        else if(phi[i]==val){
            if(i<ans)ans = i;
        }
    }
    cout<<ans<<endl;
    return
 
 0;
}