Java Fast IO (even faster than BufferedReader). Key differences: no thread safety, doesn't ensure that the input stream is still open, does not create unncessary objects

IO.java

import java.io.InputStreamReader;
import java.io.IOException;
public class IO {
    static InputStreamReader br = new InputStreamReader(System.in);
    static char[] ibuf = new char[65536];
    static int iptr = 0;
    static int imax = 0;

    static int readInt() throws IOException {
        int x = 0;
        char c;
        while ((c = getChar()) <= ' ');
        do {
            x = x * 10 + (c - '0');
        } while ((c = getChar()) > ' ');
        return x;
    }

    static char getChar() throws IOException {
        if (iptr >= imax) {
            imax = br.read(ibuf, 0, 65536);
            iptr = 0;
        }
        return ibuf[iptr++];
    }
}