http://judge.u-aizu.ac.jp/onlinejudge/review.jsp?rid=4396675#1

main.d

import std.stdio, std.string, std.algorithm, std.array, std.range, std.conv,
    std.typecons, std.math, std.container, std.format, std.numeric;

alias T = Tuple!(long, "value", long, "time");

class Segtree
{
private:
    long size;
    T[] xs;
public:
    this(long size)
    {
        long i = 1;
        while (i <= size)
        {
            i *= 2;
        }
        this.size = size;
        this.xs = new T[](i * 2);
    }

    this(long size, T value)
    {
        this(size);
        this.xs.fill(value);
    }

    void update(long l, long r, T x)
    {
        l += this.size;
        r += this.size;
        while (l < r)
        {
            if (l % 2 == 1)
            {
                this.xs[l] = x;
                l++;
            }
            l /= 2;
            if (r % 2 == 1)
            {
                this.xs[r - 1] = x;
                r--;
            }
            r /= 2;
        }
    }

    T find(long i)
    {
        i += this.size;
        T ans = this.xs[i];
        while (true)
        {
            i /= 2;
            if (i == 0)
            {
                break;
            }
            if (ans.time < this.xs[i].time)
            {
                ans = this.xs[i];
            }
        }
        return ans;
    }
}

void main(string[] args)
{
    long n, q;
    readf("%d %d\n", &n, &q);
    auto seg = new Segtree(n, T((1 << 31) - 1, -1));
    foreach (i; 0 .. q)
    {
        long cmd, s, t, x;
        readf("%d ", &cmd);
        if (cmd == 0)
        {
            readf("%d %d %d\n", &s, &t, &x);
            seg.update(s, t + 1, T(x, i));
        }
        else
        {
            readf("%d\n", &x);
            auto val = seg.find(x);
            writeln(val.value);
        }

    }

}