public int computation(char operation, int value1, int value2) throws IncorrectSymbol {
        switch (operation) {
            case '+' : return value1 + value2;
            case '-' : return value1 - value2;
            case '*' : return value1 * value2;
            case '/' : return value1 / value2;
            default : throw new IncorrectSymbol("Wrong operation symbol!");
        } 
    }