import java.util.*; import static java.lang.System.*; import java.io.*; import java.math.*; public class Main { static FastScanner sc = new FastScanner(System.in); public static void main(String[] args) { long n = sc.nextLong(); int i; long ans = n; for (i=3; i<=Math.max(3,Math.sqrt(n)); i++) { if (n%i==0) {ans = i; break;} } out.println(ans); } } class FastScanner implements Closeable { private final InputStream in; private final byte[] buffer = new byte[1024]; private int ptr = 0; private int buflen = 0; public FastScanner(InputStream in) {this.in = in;} private boolean hasNextByte() { if (ptr < buflen) {return true;} else{ ptr = 0; try {buflen = in.read(buffer);} catch (IOException e) {e.printStackTrace();} if (buflen <= 0) {return false;} } return true; } private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;} private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;} public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();} public String next() { if (!hasNext()) throw new NoSuchElementException(); StringBuilder sb = new StringBuilder(); int b = readByte(); while(isPrintableChar(b)) { sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); long n = 0; boolean minus = false; int b = readByte(); if (b == '-') { minus = true; b = readByte(); } if (b < '0' || '9' < b) {throw new NumberFormatException();} while(true){ if ('0' <= b && b <= '9') { n *= 10; n += b - '0'; }else if(b == -1 || !isPrintableChar(b)){return minus ? -n : n;} else{throw new NumberFormatException();} b = readByte(); } } public int nextInt() { long nl = nextLong(); if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException(); return (int) nl; } public double nextDouble() { return Double.parseDouble(next());} public void close() { try {in.close();} catch (IOException e) {} } }