Check nguyen to thong minh

ll check(ll n){
   if(n<=1) return 0;
   if(n<=3) return 1;
   if(n%2==0||n%3==0) return 0;
   for(ll i=5;i*i<=n;i+=6)
     if(n%i==0||n%(i+2)==0)
       return 0;
    return 1;
}