#include <bits/stdc++.h>
using namespace std;
#define omen ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define ll long long
 
bool isPrime(int num) {
    for (int i = 2; i <= sqrt(num); i++) {
        if (num % i == 0) return false;
    }
    return true;
}
 
int nextPrime(int n) {
    int current = n + 1;
    while (true) {
        if (isPrime(current)) return current;
        else current++;
    }
}
 
int main() {
    omen;
    int n, m;cin >> n >> m;
    if (isPrime(m) && nextPrime(n) == m) cout << "YES" << endl; else cout << "NO" << endl;
    return 0;
}
 

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