// Hey puzzle designer, why ????
const std = @import("std");

pub fn main() !void {
    const stdin = std.io.getStdIn();
    var buf_io = std.io.bufferedReader(stdin.reader());
    var reader = buf_io.reader();

    var buf = [_]u8{0} ** 100;
    _ = try reader.readAll(&buf);

    const stripped = std.mem.trim(u8, &buf, " \n\r\x00");
    const solution = try mine(stripped);
    std.debug.print("{d}", .{solution});
}

fn mine(key: []const u8) !u64 {
    var buf = [_]u8{0} ** 10000;
    for (1..1e10) |i| {
        const candidate = try std.fmt.bufPrintZ(&buf, "{s}{d}", .{ key, i });
        var result = [_]u8{0} ** std.crypto.hash.Md5.digest_length;
        std.crypto.hash.Md5.hash(candidate, &result, .{});

        // Check first 6 zeroes (3 bytes)
        if (result[0] == 0 and result[1] == 0 and result[2] == 0) {
            return i;
        }
    }

    return 0;
}