const std = @import("std");

fn pgcd(l: u32, r: u32) u32 {
    var a = l;
    var b = r;
    if (a == 0 or b == 0) {
        return 0;
    }
    while (a != b) {
        if (a > b) {
            a = a - b;
        } else {
            b = b - a;
        }
    }
    return a;
}

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();
    const args = try std.process.argsAlloc(allocator);
    defer std.process.argsFree(allocator, args);
    if (args.len != 3) {
        std.debug.print("Usage: find-pgcd L R\n", .{});
        return error.WrongArgs;
    }
    const l = try std.fmt.parseInt(u32, args[1], 10);
    const r = try std.fmt.parseInt(u32, args[2], 10);
    std.debug.print("PGCD({d},{d}) = {d}\n", .{ l, r, pgcd(l, r) });
}