struct Account {
    let currencyCode: String
    let openDate: Date
}

let currencyCodes = ["RUR": 0, "USD": 1, "EUR": 2]

func sortedAccounts(_ accounts: [Account]) -> [Account] {
    return accounts
        .sorted { first, second in
            let secondCurrency = currencyCodes[second.currencyCode] ?? Int.min
            let firstCurrency = currencyCodes[ first.currencyCode] ?? Int.max
            return firstCurrency < secondCurrency
        }
        .sorted { first, second in first.currencyCode == second.currencyCode && first.openDate < second.openDate }
}