SumTimeCheat.java

import java.math.BigInteger;

class Sum2 {
    private static final BigInteger MIN = BigInteger.ONE;
    private static final BigInteger MAX = new BigInteger("10000000000");
    private static final BigInteger TWO = new BigInteger("2");

    public static void main(String[] args) {
        long start = System.nanoTime();
        final BigInteger result = (MIN.add(MAX)).multiply(MAX.divide(TWO)); //Hi from mister Gauss, motherfuckers!
        long end = System.nanoTime();
        long microseconds = (end - start) / 1000;

        System.out.println(String.format("Result: %s", result.toString()));
        System.out.println(String.format("Execution time: %d", microseconds));
    }
}