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const std = @import("std");
const point = struct { x: i64, y: i64 };
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();
const alloc = gpa.allocator();
const path = "input.txt";
const fp = try std.fs.cwd().openFile(path, .{.mode = std.fs.File.OpenMode.read_only});
defer fp.close();
var reader = fp.reader();
var buffer: [256]u8 = undefined;
var points = std.ArrayList(point).init(alloc);
defer points.deinit();
while(try reader.readUntilDelimiterOrEof(&buffer, '\n')) |line| {
const i = std.mem.indexOf(u8, line, ",").?;
const p = point{
.x = try std.fmt.parseInt(i64, line[0..i], 10),
.y = try std.fmt.parseInt(i64, line[i+1..], 10)
};
try points.append(p);
}
var largest: u64 = 0;
for(0..points.items.len) |i| {
for(i..points.items.len) |z| {
if(i == z) continue;
const vol = (1 + @abs(points.items[i].x - points.items[z].x)) * (1 + @abs(points.items[i].y - points.items[z].y));
if(vol > largest) {
const len: i64 = @intCast(@abs(points.items[i].x - points.items[z].x));
const high: i64 = @intCast(@abs(points.items[i].y - points.items[z].y));
const a: i64 = @min(points.items[i].x, points.items[z].x);
const b: i64 = a + len;
const c: i64 = @min(points.items[i].y, points.items[z].y);
const d: i64 = c + high;
var pass: bool = true;
//check if any line intersects with this box, so glad this worked
for(0..points.items.len, 1..points.items.len + 1) |o,s| {
const item1 = points.items[o];
const item2 = if(points.items.len > s) points.items[s] else points.items[0];
const verticle = item1.x == item2.x;
if(verticle and (a < item1.x and item1.x < b) and !(item1.y >= d and item2.y >= d or item1.y <= c and item2.y <= c)){
pass = false;
break;
} else if(!verticle and (c < item1.y and item1.y < d) and !(item1.x >= b and item2.x >= b or item1.x <= a and item2.x <= a)){
pass = false;
break;
}
}
if(pass) largest = vol;
}
}
}
std.debug.print("{}\n", .{largest});
}
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