const std = @import("std");

const Reader = std.io.AnyReader;

pub fn main() !u8 {
    return f();
}

fn f() !u8 {
    const file = try std.fs.cwd().openFile("string", .{});
    defer file.close();

    var br = std.io.bufferedReader(file.reader());
    const r = br.reader().any();

    var n: u8 = 0;
    for (0..1_000_000) |i| {
        _ = i;
        while (r.readByte() catch null) |c| {
            n +%= try f1(r, c);
        }
        br.start = 0;
        br.end = 0;
        try file.seekTo(0);
    }
    return n;
}

fn f1(r: Reader, c1: u8) !u8 {
    if (c1 != '\\') return c1;
    const c = try r.readByte();
    if (c == 'u') return unknown1();
    return switch (c) {
        '\\', '"' => c,
        '0' => 0,
        'a' => 7,
        'b' => 8,
        't' => 9,
        'n' => 10,
        'v' => 11,
        'f' => 12,
        'r' => 13,
        'e' => 27,
        'x' => unknown2(),
        else => unknown3(),
    };
}

fn f2(r: Reader, c1: u8) !u8 {
    if (c1 != '\\') return c1;
    const c = try r.readByte();
    if (c == 'u') return unknown1();
    if (c == 'x') return unknown2();
    if (c == '\\' or c == '"') return c;
    const itable = .{ '0', 'a', 'b', 't', 'n', 'v', 'f', 'r', 'e' };
    const ctable: []const u8 = &.{ 0, 7, 8, 9, 10, 11, 12, 13, 27 };
    const i = std.mem.indexOfScalar(u8, &itable, c) orelse return unknown3();
    return ctable[i];
}

fn f3(r: Reader, c1: u8) !u8 {
    if (c1 != '\\') return c1;
    const c = try r.readByte();
    if (c == 'u') return unknown1();
    if (c == 'x') return unknown2();
    if (c == '\\' or c == '"') return c;
    if (c == '0') return 0;
    const table = comptime t: {
        var table: [26]u8 = .{0} ** 26;
        table['a' - 'a'] = 7;
        table['b' - 'a'] = 8;
        table['t' - 'a'] = 9;
        table['n' - 'a'] = 10;
        table['v' - 'a'] = 11;
        table['f' - 'a'] = 12;
        table['r' - 'a'] = 13;
        table['e' - 'a'] = 27;
        break :t table;
    };
    if (c < 'a') return unknown3();
    const result = table[c - 'a'];
    return if (result != 0) result else unknown3();
}

fn unknown1() u8 {
    return 0;
}
fn unknown2() u8 {
    return 0;
}
fn unknown3() u8 {
    return 0;
}