static boolean isPrime(int n){
boolean result=true;
if(n <= 1) return false;
for(int i = 2; i <= n/2; i++){
if(n % i == 0){
result = false; //if some number divides it, then prime=false;
break;
}
}
return result;
}
static boolean isPrime(int n){
for (int i = 2; i <= Math.sqrt(n); i++)
if (n % i == 0) return false;
return n > 1;
}