import std;

import mir.combinatorics;

void main()
{
    File("input", "r").byLine.map!(to!long)
        .array.findFirstNumberNotSumOf2PreviousNumbers(25).writeln;
}

auto findFirstNumberNotSumOf2PreviousNumbers(long[] numbers, size_t windowSize)
in(numbers.length > windowSize)
{
    return numbers.slide(windowSize + 1)
        .map!(window => tuple(window[0 .. $ - 1].combinations(2).map!sum, window[windowSize]))
        .find!(pair => !pair[0].canFind(pair[1]))
        .front[1];
}

unittest
{
    long[] input = [
        35, 20, 15, 25, 47, 40, 62, 55, 65, 95, 102, 117, 150, 182, 127, 219, 299,
        277, 309, 576
    ];

    assert(input.findFirstNumberNotSumOf2PreviousNumbers(5) == 127);
}